Is the art of depriving cotton, linen, silk, wool, wax, &c., of their colouring matter, and rendering them as white as possible. The word is probably derived from the French term blanchiment, which signifies the process of rendering white.
History.
1. The ancients, especially in Egypt, where white linen or cotton was a common article of clothing, must at an early period have been acquainted with the method of bleaching that substance; but none of their writers have left us any details on the subject. We know, however, from Pliny, that different plants, and likewise the ashes of plants, which no doubt contained alkali, were employed as detergents. Pliny mentions particularly the struthium as much used for bleaching in Greece. This plant has been considered by some as the gypsophila struthium. But as it does not appear from Sibthorp's Flora Graeca, published by Sir James Smith, that this species is a native of Greece, Dr Sibthorp's conjecture, that the struthium of the ancients was the saponaria officinalis, a plant common in Greece, is certainly more probable. Mr Parkes, in his Essay on Bleaching (Chemical Essays, vol. iv. p. 7), says, that Theophrastus states that lime was used by the ancients in bleaching; and that a ship, partly loaded with linen, and partly with lime for bleaching it, was destroyed by the water having accidentally found access to the lime. We endeavoured, with some pains, to verify this quotation; and, accordingly, turned over all the writings of Theophrastus with which we are acquainted, but without being able to find any thing bearing the least allusion to it.
Till about eighty years ago, the art of bleaching was scarcely known in Great Britain. It was customary to send all the brown linen manufactured in Scotland to Holland to be bleached. It was sent away in the month of March, and not returned till the end of October, being thus out of the hands of the merchant more than half a year. The principal Dutch bleaching-grounds were in the neighbourhood of Haarlem; and the great success of their bleaching was ascribed to the superior efficacy of their water, which, according to the fashionable theory of the time, was seawater filtered and rendered sweet by passing through their sand-downs. Indeed, it was long a prejudice on the Continent, that no water was efficacious for bleaching but sea-water.
The Dutch mode of bleaching was to steep the linen for about a week in a potash ley poured over it boiling hot. The cloth being taken out of this ley, and washed, was next put into wooden vessels containing butter-milk, in which it lay under a pressure for five or six days. After this it was spread upon the grass, and kept wet for several months, exposed to the sunshine of summer.
In the year 1749, as we are informed by Mr Parkes (Chemical Essays, vol. iv. p. 263), an Irishman, who had learned something of the art of bleaching, settled in the north of Scotland, and established a bleaching manufactory. On applying to the principal Scotch makers of linen, they readily furnished him with a quantity of goods; but after keeping them a whole year, he failed in all his endeavours to bleach them, and the proprietors were obliged to send them to Holland to get the process completed. Next summer his efforts were not more successful; the linen was considerably injured, and even rendered tender by his management, but it was not whitened. Nevertheless, this man by perseverance became in a few years an excellent practical bleacher. He had the merit of introducing the art into Great Britain, and his descendants at this day figure among the higher ranks in the metropolis.
The bleaching process, as at that time performed, was very tedious, occupying a complete summer. It consisted in steeping the cloth in alkaline leys for several days, washing it clean, and spreading it upon the grass for some weeks. The steeping in alkaline leys, called bucking, and the bleaching on the grass, called crofting, were repeated alternately for five or six times. The cloth was then steeped for some days in sour milk, washed clean, and crofted. These processes were repeated, diminishing every time the strength of the alkaline ley, till the linen had acquired the requisite whiteness.
For the first improvement in this tedious process, which was faithfully copied from the Dutch bleachfields, manufacturers were indebted to Dr Francis Home of Edinburgh, who proposed to substitute water acidulated with sulphuric acid, for the sour milk previously employed. This suggestion was in consequence of the new mode of making sulphuric acid, contrived some time before by Dr Roe-buck, which reduced the price of that acid to less than one third of what it had formerly been. It is curious, that when this change was first adopted by the bleachers, there was the same outcry against its corrosive effects as we have seen some years ago, when chlorine was substituted for crofting. No allegation, however, could be worse founded, and it was completely destroyed by the publication of Dr Home (Essay on Bleaching), who demonstrated the perfect innocence and the superior efficacy and cheapness of sulphuric acid, when properly applied, as compared with sour milk. Another advantage resulted from the use of sulphuric acid, which was of the greatest importance to the merchant. A souring with sulphuric acid required at the longest only twenty-four hours, and often not more than twelve; whereas, when sour milk was employed, six weeks, or even two months, were requisite, according to the state of the weather. In consequence of this improvement, the process of bleaching was shortened from eight months to four, which enabled the merchant to dispose of his goods so much the sooner, and consequently to trade with less capital.
The bleaching art remained in this state, or nearly so, till the year 1787, when a most important change began to take place in it, in consequence of a discovery which originated in Sweden about thirteen years before. In the year 1774 there appeared in the Memoirs of the Royal Academy of Stockholm a paper on manganese, by Mr Scheele. Among other experiments to which he subjected this mineral, he mixed it with muriatic acid, put the mixture in a retort, and applied heat. He perceived a smell similar to that of aqua regia. This induced him to collect what came over in a receiver, and he found it to be muriatic acid, altered in a remarkable manner by the action of the manganese on it. Its smell was greatly heightened, it was become less soluble in water, and it possessed the property of destroying those vegetable colours on which it was allowed to act. M. Berthollet repeated the experiments of Scheele on this new acid in 1785, and added considerably to the facts already known. He showed that this new substance (called by Scheele deplogisticated muriatic acid) is a gas soluble in water, to which it gives a yellowish green colour, an astringent taste, and the peculiar smell by which the body is distinguished. When water impregnated with this gas is exposed to sunshine, it gradually loses its colour, while at the same time a quantity of oxygen gas is disengaged from the water. If the liquid be now examined, it will be found to contain, not the new acid, but common muriatic acid. This experiment Berthollet considered as exhibiting an analysis of the new acid, and as demonstrating that it is a compound of muriatic acid and oxygen. On that account he gave it the name of oxygenated muriatic acid, which was afterwards shortened into oxy muriatic acid, an appellation by which it was long known among bleachers.
The property which this gas possesses of destroying vegetable colours led Berthollet to suspect that it might be introduced with advantage into the art of bleaching, and that it would enable practical bleachers greatly to shorten their processes. At what time these ideas first struck his mind we do not exactly know; but at the end of a paper on deplogisticated muritic acid, read before the Academy of Sciences at Paris in April 1785, and published in the Journal de Physique for May of the same year (vol. xxvi. p. 325), he mentions that he had tried the effect of the gas in bleaching cloth, and found that it answered perfectly. This idea is still further developed in a paper on the same substance, published in the Journal de Physique for 1786. In 1786 he exhibited the experiment to Mr Watt, who, immediately upon his return to England, commenced a practical examination of the subject, and was accordingly the person who first introduced the new method of bleaching into Great Britain.
Mr Parkes, in his Chemical Essays, published in 1815, has mentioned some facts upon this subject, which it will be proper to state. In the early part of the year 1787, Professor Copland of Aberdeen accompanied the Duke of Gordon to Geneva, and was there shown the discoloring property of chlorine gas by M. de Saussure. Mr Copland was much struck with the importance of the experiment; and on his return to Aberdeen in July 1787, he mentioned the circumstance, and repeated the experiment before some eminent bleachers in his own neighbourhood. These gentlemen were Messrs Milnes of the house of Gordon, Barron, and Company, Aberdeen. They immediately began the application of the process to the bleaching of linen on a great scale; and Mr Parkes assures us that they were the first persons who applied the new process to practical bleaching in Great Britain. But this statement, though it may appear plausible at first sight, is quite incorrect. The writer of this article took the liberty of applying to Mr Watt himself for information on the subject. Mr Watt has preserved copies of all his letters since the year 1782, taken by means of his copying machine; and he allowed the writer of this article to peruse such of them as bore any reference to this subject. Now, two letters were found which entirely set the matter at rest. The first of these is to his father-in-law, Mr Macgregor, dated Birmingham, 19th March, 1787. In this letter he gives a particular detail of the new bleaching process, states its advantages, and says that he had sent Mr Macgregor a quantity of the whitening liquor. The second letter is to Berthollet, and is dated Birmingham, May 9, 1787. The following is a part of that letter, which we have transcribed verbatim: "Je ne sais pas si j'ai encore fait la liqueur acide si fort que vous avez fait, mais je vous donnerais les moyens de juger. Je trouve que 4 onces de mon acide mélangé avec la quantité nécessaire d'alkali de pearl-ash peut blanchir un gros de toile brune, telle comme j'ai vu chez vous. Il est vrai qu'il ne la fait tout-à-fait blanc; mais il le fait aussi blanc, que je puis le faire, même en ajoutant une seconde dose d'acide. Je bouille la toile par avance dans une solution d'alkali faible; et, à mi blanc, je la bouille une seconde fois. Je trouve que le savon est meilleur que l'alkali pur pour la seconde bouillie. J'ai blanchi tout-à-fait le coton, mais je ne suis encore parvenu à blanchir parfaitement la toile de lin." The reader will observe that the date of both of these letters is some months before Mr Copland's return from the Continent. M. Berthollet had published his process in 1785, and as Watt had brought it to England in the end of 1786, and had put it in practice, and introduced it into Mr Macgregor's bleachfield, near Glasgow, in the month of March 1787, it is clear that Saussure has no claim to the original discovery, nor Mr Copland to the first introduction of the new process into Great Britain.
Dr Henry quotes a letter of Mr Watt, dated February 23, 1788, in which he says, "I have for more than a twelvemonth been in possession and practice of a method of preparing a liquor from common salt, which possesses bleaching qualities in an eminent degree; but not being the inventor, I have not attempted to get a patent or exclusive privilege for it." (Annals of Philosophy, vi. 423.) This letter alone is sufficient to show that Mr Watt's experiments were of an earlier date than those of Messrs Milnes. He says further, that "at that very time 1500 yards of linen were bleaching by the new process, under his directions." This great experiment was conducted in the bleachfield of his father-in-law, Mr Macgregor, near Glasgow; where, as he wrote to M. Berthollet, soon after, 500 pieces were bleached by the new method, and Mr Macgregor was so satisfied of the importance of the new process, that he had resolved to continue it. Mr Watt made several improvements in the method of M. Berthollet. Instead of employing muriatic acid and manganese, as had been done by Scheele and Berthollet, he had recourse to the cheaper mode of a mixture of common salt, black oxide of manganese, and sulphuric acid. He made use of wooden vessels to hold the water which was to be impregnated with the chlorine, coating them within with a mixture of wax and pitch, which rendered them air tight, and prevented the gas from acting on the wood. Mr Watt likewise contrived a test to indicate the strength of the water impregnated with chlorine, as far as its bleaching effects were concerned. He took a determinate quantity of the infusion of cochineal, and ascertained how much of the bleaching liquor was necessary to destroy the colour. The strength of the bleaching liquor was obviously inversely as the quantity necessary to destroy the colour. But M. Welter hit upon another method about the same time, which has been considered as preferable, and has in consequence come into general use. He employed a solution of indigo in sulphuric acid, instead of the infusion of cochineal. In other respects the two methods were the same.
Mr Thomas Henry of Manchester began his experiments on bleaching by means of chlorine nearly as early as Mr Watt, and without any previous knowledge of what he had done. He was very assiduous, and very successful in his trials. At a meeting of the bleachers held at Manchester early in 1788, he exhibited half a yard of calico, bleached by the new method, which was considered as superior in whiteness to half a piece of calico bleached by the same process by Messrs Cooper, Baker, and Charles Taylor. In consequence of this exhibition he was applied to by Mr Ridgway of Horwich, to be instructed in the new process; and the instructions which the latter accordingly received were the first step of a series of improvements carried on by Mr Ridgway and his son, with an ability and spirit of enterprise which have raised their establishment to its present extent and importance. (See Annals of Philosophy, vi. 423.) These two gentlemen, Messrs Watt and Henry, had the chief merit of introducing the new mode of bleaching into Lancashire, and the neighbourhood of Glasgow.
In the year 1789 M. Berthollet published a memoir on the subject, in the second volume of the Annales de Chimie, p. 151. In this memoir, which constituted the first publication on the mode of bleaching by means of chlorine, Berthollet gives a detail of the progress of his experiments, and states the attempts that had been made to introduce the new mode of bleaching into France. M. Bonjour, who had assisted him in his experiments, associated himself with M. Constant, a manufacturer of cloth at Valenciennes, to form a bleaching establishment in that city upon the new plan. But their project was prevented by the prejudices of the inhabitants and by the jealousy of the bleachers, who were afraid of being injured by the introduction of any new improvements. M. le Comte de Bellaing, however, who approved of the project, granted a piece of ground possessed of all the requisite conveniences, but at rather too great a distance from Valenciennes. Mr Bonjour applied to the board of commerce for the exclusive privilege of bleaching for some years, according to the new method in Valenciennes and Cambrai, and for two leagues around these places, offering at the same time to explain the new process in all its details to those who wished to make themselves acquainted with it. But the request was refused.
It does not appear from Berthollet's account that the new mode of bleaching had been successfully established in any manufactory in France before the publication of his Memoir. One of the great difficulties in the way of applying chlorine to bleaching, was the very disagreeable and noxious odour which characterized it, and which rendered it not only very offensive, but highly injurious to the health of the workmen. Berthollet describes, at consider-
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1 The writer of this article, when he drew up the preceding historical detail for the Supplement to the Fourth Edition of the Encyclopedia Britannica in the year 1816, thought it right to write to Professor Copland, stating the facts given in the text, and requesting him to say whether they were accurate. Mr Copland returned no answer to the letter. This silence may be considered, we think, as an admission of the accuracy of the statements. He was at that time engaged in a course of lectures on Bleaching, dyeing, printing, and bleaching. An acquaintance with the properties of chlorine, which he had repeatedly had occasion to exhibit in his course of lectures, and the general hints previously thrown out by Berthollet, led him to conclude that the liquor of Bourbollon and Company could be nothing else than chlorine, or some compound of it. His first operations on the large scale consisted in exposing the goods, in a moist state, in air-tight chambers, to the action of chlorine gas. He likewise began to prepare for sale a bleaching liquor, in which the gas was condensed in a very weak solution of potash; which, as we learn from Berthollet, was the very same with the Lessive de Javelle. This liquid possessed two advantages over water simply impregnated with chlorine gas. Its smell was less noxious, and it might be employed to whiten printed calicoes without destroying the colours which had been dyed upon the cloth. But these advantages were much more than counterbalanced by equivalent disadvantages. It was found not to go nearly so far as water impregnated with chlorine gas, and when kept for some time it lost its bleaching properties altogether. The reason of this last alteration is now sufficiently understood: the chlorine in the liquid was gradually converted into common muriatic acid and chloric acid; the water containing merely common muriate of potash and chlorate of potash. In consequence of these disadvantages, the addition of potash to the bleaching liquid was soon laid aside. The next attempt to destroy the noxious smell of the liquid, without destroying its bleaching property, was the addition of lime to the liquid. Mr Henry of Manchester was one of the first persons who thought of this addition. On the floor of his air-tight chambers rested a stratum of thin cream of lime, through which the goods were passed by means of a wince; and were afterwards exposed, on quitting the liquor, to chlorine acid gas. Hence the chloride of lime was formed upon the cloth. But this method was objectionable in the case of some coloured goods, the colours of which were injured or destroyed by that earth. It admitted, therefore, of only a partial application.
Other persons made similar attempts, none of which appear to have been attended with success. But Mr Tennant of Glasgow, after a great deal of most laborious and acute investigation, hit upon a method of making a saturated liquor of chloride of lime, which was found to answer perfectly all the purposes of the bleacher. This was certainly a most important improvement. Without it, the prodigious extent of business carried on by some of our bleachers could not possibly have been transacted. To give some idea of the rapidity with which bleaching is conducted according to the new process, we may mention the following fact, which we state on what we consider as very good authority. A bleacher in Lancashire received 1400 pieces of gray muslin on a Tuesday, which on the Thursday immediately following were returned bleached to the manufacturers, at the distance of sixteen miles, and they were packed up and sent off on that very day to a foreign market. The quick return of capital which is thus made is a benefit entirely to be ascribed to the new mode of bleaching.
In the year 1798 Mr Tennant took out a patent for his new invention, and offered the use of it to practical bleachers, for a fair and reasonable portion of the savings made by its substitution for potash, then in general use. Many of the bleachers, however, used it without paying him, and a combination was formed to resist the right of the patentees. In December 1802, Mr Tennant and Company brought an action for damages against Messrs Slater and Varley, nominally the defendants, but who, in fact, were Bleaching, backed and supported by a combination of almost all the bleachers in Lancashire. In consequence of this action, the patent right was set aside by the verdict of a jury and the decision of Lord Ellenborough, who used very strong language against the patentees. The grounds of this decision were, that the patent included a mode of bucking with quicklime and water, which was not a new invention. It was decided that, because one part of the patent was not new, therefore the whole must be set aside. Had the writer of this article constituted the jury, the verdict would have been very different. Lime was indeed used previous to the patent of Mr Tennant; but it was employed in a quite different manner from his, and he would have allowed all of them to continue their peculiar method without any objection, because it would have been productive of no injury to his emolument. If the very same process as that of Mr Tennant was employed before he took out his patent, there could be no doubt that the process originated with him, and that those who used it had been induced to do so from the information which they derived from him. In the opinion of the writer of this article, Mr Tennant was hardly used, and the words employed by Lord Ellenborough were quite inapplicable to him. But when a very powerful combination is formed against any individual, the sentiments with which they are actuated propagate themselves with rapidity; and it is difficult for the most upright jury to avoid being swayed by prejudices, which are the more formidable, that their existence is not perceived.
In consequence of this decision, the use of liquid chloride of lime in bleaching was thrown open to all, and appears now to be universally employed by the bleachers in Britain. Mr Tennant, thus deprived of the fruits of several years of anxious and laborious investigation, advanced a step farther, to what may be considered as the completion of the new method. This consisted in impregnating quicklime in a dry state with chlorine. He had taken out a patent for this on the 13th of April 1799, and his right fortunately was not contested. He began his manufactory of solid chloride of lime at first upon a small scale, which has been ever since gradually extending, and his manufactory is now the largest of the kind in Great Britain. During the whole period of the duration of his patent he laboured under great disadvantages. The chlorine gas with which the lime was impregnated was obtained from common salt. Now, his patent did not extend to Ireland, in consequence of which manufactures of dry chloride of lime were established in that kingdom. In Ireland the manufacturer obtained his salt duty free, while Mr Tennant was obliged to pay a duty of 7s. 6d. per bushel. Such, however, was the superiority of the methods employed by Mr Tennant, that he was able to compete with the Irish manufacturers in their own country.
In the year 1815, in consequence of the joint application of the bleachers, the duty on common salt, formerly charged upon all bleachers and others who employed that article in the preparation of a bleaching liquid, was taken off, and they were henceforth allowed to use it duty free. But this act, while it affords great advantages to bleachers on a large scale, precludes those who only work on a small scale from making their own chloride of lime; the consumption of the powder, therefore, is likely to increase very much among the little bleachers and calico printers. Its use is also considerable in partially discharging the colour of Turkey red cloth. The method was originally a French invention; but a patent was granted to Mr Thomson, a Lancashire calico-printer, for the process, which, we believe, he imported from Jouy. The method is this: An acid paste, consisting of tartaric acid, or any other acid thickened with gum, is first printed on the Turkey red cloth, which is then passed through liquid chloride of lime. It becomes white only where the acid was applied. On this bleached part any other colour may be applied, and the combinations produced are exceedingly beautiful and striking.
Such, as far as we are acquainted with the subject, is the history of the progress of the new method of bleaching in Great Britain. We have said nothing of the Irish bleachers, because we are not particularly acquainted with the progress of the new method in that country, though we believe that chlorine was tried by the Irish bleachers almost as early as it was in Great Britain. Mr Parkes supposes that Mr Kirwan might have proposed the trial of the new re-agent, in consequence of some suggestion from Scheele or Saussure. (Parkes's Chemical Essay, iv. 43.) But we have no evidence that this was the case. Indeed, it would be quite unreasonable to attempt, by such vague suspicions, to detract from the merit due to Berthollet for his original suggestion of the application of chlorine to bleaching, a merit which he has enjoyed without a competitor for thirty years. Scheele was dead before any one attempted to introduce the new gas into bleaching, either in Great Britain or Ireland; and there is every reason for believing that Saussure's knowledge of the bleaching qualities of chlorine originated from Berthollet's publications on the subject in 1785 and 1786.
1.—Bleaching of Cotton.
Cotton is a kind of down which fills the seed-pods of various species of plants, particularly the Gossypium herbaceum, hirsutum, and arboreum, from all of which it is extracted in considerable quantity for the purposes of manufacturers. This substance was known to the ancients, and made by them into thread and cloth. Cotton cloth appears to have been generally worn in Egypt and the neighbouring countries at a very early period; and no doubt the plant was cultivated in India and China for similar purposes before the time at which the history of these nations, as far as we are acquainted with it, commences. Pliny gives a short description of the gossypium which grew in Upper Egypt, which is sufficient to show us that it was the same with our cotton plant. "Superior pars Aegypti in Arabiam vergens gignit fruticem, quem aliqui gossipion vocant, plures xylon, et idonea lina inda facta xylina." Parvus est, similemque barbare nucis defert fructum, cujus ex interiore bombhyce lanugo netur. Neculla sunt eis in candore mollitave preferenda." (Plini, Natur. Hist. lib. xix. c. 2.) The byssus mentioned in the same chapter was probably likewise a species of cotton; though the account of it given by Pliny is not sufficiently precise to enable us to make out the point with certainty.
Since the discovery and colonization of America and the West Indies, and our great connection with the East Indies, cotton has become a very common article of clothing in Europe. The manufacture of cotton cloth in consequence has increased prodigiously, and in Great Britain constitutes one of the great branches of manufacturing industry. The quantity of colouring matter in cotton is much less than in linen, and it is more easily removed. Hence the bleaching of cotton is much easier, and occupies less time, than that of linen. On that account it will answer best to give the reader a clear idea of the pro-
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1 The idea of saturating slacked lime with chlorine was first suggested by Charles M'Intosh, Esq. of Cross-Basket, who was at that time a partner of Messrs Tennant and Knox. The bleaching of cotton is practised chiefly in Lancashire and the neighbourhood of Glasgow, to which districts the cotton manufacture is almost confined. We shall describe the processes as they are followed in the most extensive bleaching-houses, where they have been brought to the state of greatest perfection. The processes are numerous, though each is sufficiently simple. Let us follow the cotton cloth, from the time that it comes into the hands of the bleacher till it is returned to the merchant fully bleached and ready for sale.
1. The first process is to stamp the proprietor's name upon the end of every piece of goods, that there may be no mistake from the mixture of the cloth belonging to different persons, but that every individual may have his own goods returned to him again without the least risk of error. The substance used for the purpose is coal-tar, which distills when pit-coal is heated in iron retorts for the purpose of obtaining coal-gas. It consists of a mixture, or rather solution, of black bituminous matter in naphtha. A quantity of coal-tar is spread over a woollen sieve with a brush. A wooden stamp containing the name of the proprietor of the cloth is pressed against the cloth. It takes up the requisite quantity of coal-tar, and when pressed against the end of the piece makes a black and very distinct impression of the name, which withstands all the subsequent processes to which the cloth is to be subjected without being obliterated; but which might be removed were the stamped part of the cloth to be well washed with soap, and rubbed hard between the hands of the washer.
2. The cloth thus marked is in the next place singed, in order to remove the numerous hairs or flecks of cotton, which would have the effect of injuring the look of the cloth. This is usually done by passing the pieces with a uniform velocity over an iron heated red-hot. The heat is sufficient to burn off the hairs; but the cloth passes too rapidly to be injured by the hot iron. Some years ago Mr Hall of Nottingham contrived a very ingenious apparatus, by means of which the cloth is singed by coal-gas. Some idea may be formed of the nature of the process by the following imperfect description. A represents the gas flame issuing from a pipe, and B the cloth drawn uniformly along, with the requisite velocity, to prevent it from catching fire from the flame; C represents the section of a kind of vessel terminating in a tube D, which is connected with an air-pump kept working during the whole process. The consequence is, that the cloth presses rather forcibly against the bottom of C, and the flame is cut off by the cloth without passing through it, singeing only one side of it.
3. If the cloth were thrown into a vessel of water, regularly folded into a number of plies, the water would not be able to penetrate through it, but the central folds would remain dry. To prevent this, each piece of cloth is pulled into a band, by drawing it between the hands so as to give it a slight resemblance to a rope. This band is folded loosely, and tied up by one of its ends into a kind of irregular bundle. These bundles are thrown one after another into a large square cistern or vessel, filled with cold water, and left in that situation till they are completely soaked. They are then washed in a wash-wheel, of which a representation is annexed. The wash-wheel is a cylindrical box revolving on its axis. It has four divisions, as shown by Bleaching. The dotted lines, and an opening into each division. Two pieces are put into each, abundance of water is admitted behind, and the knocking of the pieces as they fall from one division to another constitutes the washing. The process lasts from four to six minutes. The object of it is to remove as much of the weaver's dressing as possible from the cloth before the regular bleaching processes commence.
4. The next process to which the cloth is subjected is boiling with lime. This is done in a large circular boiler, or kier as it is termed, of which a section is given in the margin. It has two parts; the pan of wrought iron A, set in brick-work, on which the fire acts; and the upper part B, which is of cast-iron, and which contains the goods to be boiled. These parts are separated by a cast-iron false bottom C. D is an iron pipe placed in the centre of the kier, and resting upon the false bottom. The liquid in the pan A, from the pressure upon it, does not boil till it is heated considerably above the boiling point. At last it begins to boil in a part of the pipe D, where the pressure is less than in the pan. A mixture of steam and water is formed there, producing a column of lower specific gravity than before. This rushes up the pipe, and is thrown back by the cap E into the boiler, making room for another portion of highly heated liquid, which rising also in the pipe, boils in its turn, making room for a third portion, and so on till the pan is emptied of all its liquid above the bottom of the pipe. The liquid then filters gradually through the goods in the vessel B into the pan, where in a few minutes it is again heated to the requisite degree, and again rushes up the pipe as before. This process lasts about eight hours after boiling commences.
Another kind of boiler, in which the water is heated by steam from a separate boiler, is now very general use. It consists of a cylindrical vessel AA, 9 feet wide, of wood or iron, having a false bottom BB, on which the goods are placed, about six inches from the real one. A small pipe E, in the centre of a wider one CC, conveys the steam from the steam-boiler. When the liquid boils at the bottom, where the steam issues, the steam forces its way Bleaching up the pipe CC, carrying with it a quantity of the ley, which is thrown back by the small cover D, spreads itself over the surface of the goods, and filters through them into the space below the false bottom, where it is again heated by the steam, re-ascends the pipe CC, and so on in constant succession, till the alkali is exhausted. FF is a wooden cover which prevents the cooling of the materials below a boiling heat.
The quantity of lime used in this process is 1 lb. of lime for every 35 lbs. of the cloth. This lime, previously slackened, is mixed with water in a separate vessel, till it has acquired the consistency of cream. A layer of pieces of cloth is deposited in the boiler, and over it is spread equally a portion of this cream of lime. Then another layer of goods is introduced over the former, which is covered with cream of lime as before. In this way the goods and cream of lime are introduced in alternate layers, till the whole has been put into the boiler; then the requisite quantity of water is introduced, and the process of boiling begun.
The cloth as it comes from the hands of the weaver is impregnated with the dressing, which consists of flour boiled with water into a paste. It contracts also unavoidably many greasy stains, which become visible to the eye when the piece is put into water, by remaining dry, while the remainder of the cloth is wetted. These two impurities are removed by the lime-boiling more effectually, it appears, than they would be if a potash or soda ley were used for the purpose.
The colouring matter of the cotton, which it is the object of bleaching to remove, is also acted upon by the lime, but certainly not removed; for the colour of the cloth after it has undergone the lime-boiling is darker than it was before it was wetted at all. Yet it cannot be doubted that this colouring matter has been acted on by the lime, and that it is rendered more easily removable by the future processes to which the goods are subjected.
After the lime-boiling, the cloth is carefully washed in the wash-wheel, in order to remove the lime, loaded as it is with impurities, as completely as possible from the cloth.
5. The cloth is now subjected to the action of the bleaching powder.
The bleaching powder, or chloride of lime as it is usually called, is made by exposing slackened lime to an atmosphere of chloric gas till it refuse to absorb any more. Unslackened lime is incapable of absorbing this gas; but slackened lime, or hydrate of lime, absorbs it readily. Mr Tennant of Glasgow, who was the original contriver of the process, and is still by far the greatest maker in Great Britain, prepares it by covering the floor of a stone chamber with a layer of slackened lime to the height of a few inches. The stone of which the chamber is built is the Glasgow coal sandstone, which is rendered impervious to the chlorine by being coated externally with a layer of cement, made by melting together wax and rosin in the requisite proportions to make a stiff but very ductile cement. The wooden door of the apartment is then closed and made air-tight. There is an aperture above, which can be occasionally opened: the use of which seems to be to allow the common air of the chamber to make its escape. A mixture of native black oxide of manganese, ground to a fine powder, of common salt, and of sulphuric acid diluted with water, is put into a large leaden vessel, nearly spherical, and furnished at the top with a lid, which fits so as to be air-tight. From this lid a leaden tube passes into the lime chamber, to convey the chlorine gas as it is formed. This leaden vessel is cased on the outside with an iron vessel, between which and the leaden vessel there is an interval.
At first the chlorine gas is extricated without any heat being applied; but after the process has continued for some time, a current of steam is made to pass into the inside of the iron case, which heats the leaden still sufficiently high to continue the process till the whole common salt is decomposed, and of course the disengagement of chlorine gas is at an end.
The black oxide of manganese (supposing it pure) is a compound of
\[ \begin{align*} 1 \text{ atom manganese} &= 3.5 \\ 2 \text{ atoms oxygen}... &= 2 \\ &= 5.5 \end{align*} \]
By the mutual action of the sulphuric acid and the acid of the common salt it is converted into protoxide of manganese, composed of
\[ \begin{align*} 1 \text{ atom manganese} &= 3.5 \\ 1 \text{ atom oxygen}... &= 1 \\ &= 4.5 \end{align*} \]
It therefore loses an atom of oxygen. This atom unites with the hydrogen of the muratic acid evolved, forming water, and thus converting the muratic acid into chlorine. It is obvious from this, that if the black oxide of manganese were pure, every 5.5 parts of it would be sufficient to generate 4.5 parts of chlorine, which is the quantity contained in 7.5 parts of common salt. Hence the proportions of black oxide and common salt which ought to be used are \(5\frac{1}{2}\) of the former to \(7\frac{1}{2}\) of the latter. But the black oxide of manganese employed in this country is never pure. It is always contaminated with a quantity of peroxide of iron, seldom less than one fourth of the weight of the ore, and often amounting to one third of that weight. It contains also not unfrequently barytes or lime, which seem to be in chemical combination with a portion of the oxide. On this account it is always necessary to use more than \(5\frac{1}{2}\) of manganese for every \(7\frac{1}{2}\) of salt. We believe that the quantity of black oxide for every \(7\frac{1}{2}\) parts of common salt ought not to be less than 8 parts, to make sure of obtaining the whole chlorine from the common salt.
The black oxide of manganese having a specific gravity of 4.97, and being insoluble in water, speedily falls to the bottom of the leaden still, and would soon cease to convert the muratic acid into chlorine. To prevent this, there is an agitator in every leaden vessel, which is very frequently moved by the workmen whose province it is to take charge of these stills. By this means the manganese, which is in very fine powder, is mixed with the whole liquid, and thus brought into contact with the nascent muratic acid, which it deprives of its hydrogen, and thus converts into chlorine.
To decompose \(7\frac{1}{2}\) parts of common salt completely, 12\(\frac{1}{2}\) parts of sulphuric acid of the specific gravity of 1.843 are requisite. This acid should be previously diluted with at least its own bulk of water; or it is better (when the manufacturer of bleaching powder makes his own acid, which is generally the case) to employ the sulphuric acid in the state in which it comes from the leaden chambers, without any artificial concentrations. This, if the acid maker conducts his process properly, may be as high as 1.75. Mr Tennant finds it better to employ a still greater quantity of acid than \(12\frac{1}{2}\) for every \(7\frac{1}{2}\) of salt; because the decomposition goes on with the application of less heat, and the leaden stills are much less corroded than when a smaller quantity of acid and a stronger heat are employed. What remains in the still after the evolution of the chlorine gas is at an end, is a mixture of sulphate of manganese, bisulphate of soda, and free sulphuric acid. It would not do to lose the free sulphuric acid. The residue is therefore mixed with as much common salt as the sulphuric acid is able to decompose, and the whole is gradually fused in a furnace. By this fusion the sulphate of manganese is decomposed as well as the common salt, and there remains sulphate of soda mixed with oxide of manganese and peroxide of iron. Lixiviation gets rid of these two oxides, and leaves a solution of sulphate of soda, which is evaporated to dryness, mixed with pounded coal, and ignited in a reverberatory furnace. By this simple process the Glauber salt is converted into sulphuret of sodium, from which carbonate of soda is extracted by simple and well-known processes.
The bleaching powder, when first prepared, was a dichloride of lime, or a compound of one atom of chlorine and two atoms of lime. But of late years Mr Tennant has improved his process so much, that it is now a chloride of lime, or a compound of one atom chlorine and one atom lime; that is to say, it contains twice the quantity of chlorine which it originally did, and goes twice as far when employed in bleaching; and other manufacturers have been obliged to follow his example. Hence the value of the bleaching powder all over Great Britain is about doubled, while its price is reduced to less than one half of what it was originally; being sold at present at the rate of threepence per pound, containing nearly half its weight of chlorine.
With respect to the nature of bleaching powder, no experiments have been made sufficiently decisive to remove all doubts. The most commonly received opinion is, that it is a compound of chlorine and lime, or a chloride of lime. The objection to this opinion is, what happens when carbonate of soda is saturated with chlorine to form the disinfecting liquor used by Labaraque. If the solution be evaporated, a peculiar salt is obtained, which possesses bleaching properties. No chlorine gas is given off during the evaporation. The same phenomena take place when carbonate of potash is saturated with chlorine. From this it has been conjectured, that when chlorine acts upon slackened lime, a certain portion of the lime is converted into calcium, while a portion of the chlorine is converted into chlorous acid, or a compound of one atom of chlorine and three atoms of oxygen. On this supposition it is evident that three fourths of the lime are converted into calcium. The three atoms of oxygen thus evolved convert one atom of chlorine into chlorous acid. This chlorous acid unites with the one fourth of lime remaining, and converts it into chlorite of lime; while the three atoms of calcium evolved, uniting each with an atom of chlorine, constitute chloride of calcium. According to this view of the subject, the strongest bleaching powder will be a mixture of
\[3 \text{ atoms chloride of calcium} = 21\] \[1 \text{ atom chlorite of lime} = 11\]
So that about one third of the weight is chlorite of lime, to which alone the bleaching powers of the substance is owing.
It is rather inconsistent with this opinion, that bleaching powder does not attract moisture from the atmosphere with nearly so much rapidity as might be expected from a mixture containing two thirds of its weight of so deliquescent a salt as chloride of calcium; unless, indeed, this be prevented by the chloride and chlorite being united into a double salt. When sulphuric acid or muriatic acid, however diluted, are poured into a solution of bleaching powder, chlorine gas is given out in abundance. This seems rather inconsistent with the notion of its being a mixture of chloride of calcium and chlorite of lime; at least no such evolution takes place when these acids are mixed with solutions of chloride of calcium or chlorate of potash.
The bleaching powder, in order to be applied to the cloth, must be dissolved in water; and the quantity employed for the first process consists of a solution of 24 lbs. of bleaching powder in 60 gallons of water.
In general, a solution of one pound of bleaching powder in one gallon of water has a specific gravity of 1·05. But the specific gravity of the bleaching powder solution into which the cloth is put is only 1·02. The quantity of liquor of this specific gravity necessary for 700 lbs. of cloth is 971 gallons. Hence it is obvious that the quantity of bleaching powder required for 700 lbs. of cloth will be 388½ lbs.
But the specific gravity of the solution is not sufficient to determine its qualities as a whitening substance. The longer bleaching powder is kept, especially if it be not well shut up from the action of the atmosphere, the less bleaching power does it possess. We have purchased it from apothecaries in London a great many years ago almost totally inert; yet this inactive substance was soluble in water, and was capable of augmenting the specific gravity of the liquid as much or nearly as much as the best bleaching powder whatever; but the liquid was merely a solution of chloride of calcium. Some other method, accordingly, of judging of the goodness of bleaching powder is necessary for the bleachers. The method commonly employed by the bleachers is the indigo test, first brought into use by M. Welter.
The mode of applying the indigo test followed in this country is by means of the graduated glass tube, figured in the margin, which is known by the name of the Test-tube. The method is as follows: One part of the best indigo is dissolved in nine parts of strong sulphuric acid, and the solution is mixed with 990 parts of water, making a solution, 1/10th part of which is indigo. Of this liquid a quantity is to be poured into the test-tube, so as to fill it up to 0, or the commencement of the scale. The bleaching liquor whose power is to be tried is then to be dropped gradually in, and mixed with the blue liquor by shaking the tube from time to time till the blue is changed into a clear brown. As soon as this takes place, the degree of the scale to which the mixture reaches is observed, and the figure marked at that degree indicates the strength of the steep-liquor. The lowest on the scale is, of course, the strongest in bleaching power, being capable of destroying most colour. The liquor whose strength is thus ascertained is denominated steep-liquor, of 1, 2, 3, 4, 5, and 6 degrees, the last of which is the weakest ever used for any kind of goods. By adding stock-liquor when the steep-liquor is too weak, and water when too strong, this liquor may be obtained of any strength which is required.
This mode of testing is obviously defective, because we have no good method of determining the goodness of the indigo itself employed as the test; and yet it is well known that different indigos vary considerably in the quantity of colouring matter which they contain. Various attempts have been made to improve it; but at best it can only be considered as enabling us to compare between the relative values of the different varieties of bleaching powder. It can never give us the absolute quantity of oxygen which the bleaching powder is capable of disengaging, upon which its bleaching powers must entirely depend.
But Mr Dalton, in his paper On Oxymuriate of Lime, in the Annals of Philosophy, vol. i. p. 15, has pointed out a Bleaching process, which, when a little modified, as it has been by Mr Walter Crum, one of the most extensive bleachers in the neighbourhood of Glasgow, answers exceedingly well, and enables us to determine the true quantity of oxygen which the solution of the bleaching powder is capable of yielding to the cloth. Mr Crum's method is this. He dissolves four ounces of green sulphate of iron in hot water, and then adds solution of bleaching powder by small quantities at a time till the smell of chlorine begins to be perceptible. This is a proof that the whole of the protoxide of iron in the four ounces of green vitriol has been converted into peroxide. The strength of the bleaching powder liquid employed by Mr Crum, when the object is to test its value as a bleaching ingredient, is one pound of bleaching powder dissolved in one gallon of water. Of this he adds quantities by \( \frac{1}{3} \) th of a gallon at a time to the solutions of green vitriol, till the smell begins to become sensible. Six of these measures may be added at once without any risk of evolving any smell; but on the addition of the seventh measure it is necessary to proceed with caution, adding only a little at a time, lest the point of saturation be exceeded. Let us suppose that \( \frac{7}{2} \) measures were necessary to evolve the smell of chlorine; as 64 measures contain one pound of bleaching powder, it is obvious that \( \frac{7}{2} \) measures will contain 820-3 grains. We learn from the experiment, that in the case in question 820-3 grains of bleaching powder, when placed in contact with protoxide of iron, are capable of converting all the protoxide of iron contained in four ounces of green vitriol into peroxide. Now, crystallized sulphate of iron is composed of
\[ \begin{align*} 1 \text{ atom sulphuric acid} & : 5 \\ 1 \text{ atom protoxide of iron} & : 4.5 \\ 7 \text{ atoms water} & : 7.875 \\ \end{align*} \]
Consequently four ounces of the salt must contain 396-2 grains of protoxide of iron, to convert which into peroxide will require 44 grains of oxygen. This, of course, is the quantity of oxygen contained in 820-3 grains of the bleaching powder tried. If six measures had been sufficient instead of \( \frac{7}{2} \), then 656\( \frac{1}{2} \) grains of bleaching would yield 44 grains of oxygen. In general, the bleaching powder employed by the bleachers is of about this strength. Hence it is obvious (admitting bleaching powder to be a mixture of one atom chlorite of lime and three atoms chloride of calcium) that 656\( \frac{1}{2} \) grains of bleaching powder, in the strongest state in which it is usually employed by bleachers, is composed of
\[ \begin{align*} \text{Chlorite of lime} & : 177.8 \\ \text{Chloride of calcium} & : 339.4 \\ \end{align*} \]
Loss \( : 139 \)
Total \( : 656.2 \)
This loss must be partly water, and partly perhaps owing to the presence of a greater quantity of chloride of calcium than ought to be present. If we suppose the whole of the loss to be water, then the best bleaching powder would be a compound of
\[ \begin{align*} 1 \text{ atom chlorite of lime} & : 11 \\ 3 \text{ atoms chloride of calcium} & : 21 \\ 8 \text{ atoms water} & : 9 \\ \end{align*} \]
But in general the whole lime is not accurately saturated with chlorine. Accordingly, when the bleaching powder is dissolved in water, a small residue almost always remains undissolved. Unless the powder be fresh made, a portion of chlorite is always converted into chloride of lime. It is probable, therefore, that the best bleaching powder, as it comes into the hands of the bleachers, consists of
\[ \begin{align*} 1 \text{ atom chlorite of lime} & : 11 \\ 3 \text{ atoms chloride of calcium} & : 21 \\ 6 \text{ atoms water} & : 6.75 \\ \text{Impurity} & : 2.25 \\ \end{align*} \]
If we consider the bleaching powder as a compound of chlorine and lime, our mode of calculating will not be altered. Instead of 1 atom chlorite of lime and 3 atoms chloride of calcium, we shall have 4 atoms chloride of lime, 6 atoms water, and 2.25 of impurity as before.
Sulphate of manganese might be substituted for sulphate of iron. The result would be the same, excepting that the protoxide of manganese is converted into the native black oxide, by uniting with an additional atom of oxygen. And as crystallized sulphate of manganese is composed of
\[ \begin{align*} 1 \text{ atom sulphuric acid} & : 5 \\ 1 \text{ atom protoxide of manganese} & : 4.5 \\ 4 \text{ atoms water} & : 4.5 \\ \end{align*} \]
it is obvious that \( \frac{1}{4} \) of sulphate of manganese will go twice as far, as a test of bleaching powder, as 17-375 of sulphate of iron. Thence 1\( \frac{3}{4} \) oz. of crystals of sulphate of manganese will go just as far, as a test for bleaching powder, as 4 oz. of sulphate of iron. The manganese is thrown down in the state of native black oxide; not however pure, but every six atoms of it are combined with one atom of lime, constituting a compound which may be called sex-manganite of lime, composed thus:
\[ \begin{align*} 6 \text{ atoms black oxide} & : 33 \\ 1 \text{ atom lime} & : 3.5 \\ \end{align*} \]
Prussian blue might also be employed as a test for bleaching powder. A solution of bleaching powder dissolves prussiate of iron, and the solution, when just neutral, is green; when there is an excess of bleaching powder, the liquid becomes brownish yellow. But prussiate of iron can only be employed as a comparative test in the same way as indigo; although it is preferable to indigo, because it can always be obtained of the same relative strength or purity.
The cloth is left in the cold solution of bleaching powder after six hours. It is then taken out and washed with water. It has now assumed a kind of light grey colour. It is not yet white, but much whiter than when it came into the hands of the bleacher.
6. The next process to which it is subjected is called souring. Eight gallons of the sulphuric acid of commerce are mixed with 200 gallons of water. This constitutes a liquid having a decidedly sour taste, but too dilute to be in the least corrosive. In this liquid it remains cold for about four hours. It is then taken out and carefully washed in cold water, to remove the acid as completely as possible. By the souring the cloth is rendered much whiter than it was before. The sulphuric acid dissolves and removes the oxide of iron with which the cloth is always more or less contaminated. It removes also the lime which the cloth had imbibed partly from the lime-boiling and partly from the bleaching liquor in which it was so long immersed. The colouring matter of the cloth would seem to combine with the sulphuric acid, and to form a compound much whiter than the uncombined colouring matter itself. That it is not removed is obvious from this, that if the cloth be steeped in an alkaline solution, the dark colour is again in some measure restored.
7. The cloth, after being well washed in cold water, is immersed in an alkaline ley, in which it is boiled for eight hours, precisely in the same way as was described when giving an account of the lime-boiling. Thirty-two pounds of potash made caustic by quicklime are used for every 2100 lbs. of the unbleached cloth. Of late years, in consequence of the reduced price of carbonate of soda, and its much greater purity, it has been substituted for potash by the bleachers. When the carbonate of soda is in crystals, 18 lbs. of it are equivalent to 9 or 10 lbs. of potash.
After this boiling the cloth is again carefully washed in cold water.
8. A solution of bleaching powder is now prepared, two thirds of the strength of the first bleaching powder liquid, in which the cloth is immersed, and left for five or six hours; but by this exposure the bleaching powers of the liquid are not exhausted, so that by an additional supply of strong liquor it may be rendered fit for another process.
If the cloth to be bleached has red ends, which is sometimes the case, it is carefully washed after this exposure to the action of the bleaching liquor before it is subjected to souring; but if there be no red ends this washing is dispensed with.
9. The next process is a souring. The mixture of sulphuric acid and water is nearly of the same strength as before, and the cloth is left immersed in it about four hours, or sometimes not so long. By this process the bleaching of the cloth is completed, for it comes out of the acid steep quite white.
It is a very material thing to remove all trace of the sulphuric acid from the cloth as completely as possible; because any portion of it remaining would corrode and destroy the cloth, especially when it was exposed to the action of heat. To accomplish this necessary result, the cloth is subjected to very careful washing; and this washing process is repeated two several times.
10. Such are the processes of bleaching cotton cloth when of the best quality, and carried to the greatest extent. In many cases several of the processes are omitted; but we thought it right to give a detail of them all as they are applied to cotton shirting, and to the better cotton fabrics that are to undergo the subsequent processes of calico printing. But after the bleaching is finished, the cloth is put through a variety of subsequent processes by the bleacher, in order that it may please the eye of the purchaser, and be in the best possible state for commanding a ready sale. Of the most important of these processes it will be requisite to give a short account.
The cloth is squeezed after washing, in order to remove a considerable portion of the water which it had imbibed in the washing. This is done by making it pass between two rollers, which by their pressure force out the water. There is something ingenious in this process, simple as it is, that deserves to be noticed. The pieces of cloth, as they come out of the washing wheel, are crumpled together, and frequently entangled in irregular knots. If these knots were allowed to enter between the rollers, they would, from their too great size, be apt to derange them, and might even stop the motion of the machinery altogether. To prevent this from happening, a water cistern, the top of which is on a level with the floor of the room, and which is constantly kept full of water, is placed immediately before the rollers. Over this water the cloth is made to pass on its way to the rollers. By the force necessary to drag it through this water, the piece is stretched, and any wrinkles or knots into which it may have been cast are effectually removed. Thus the cistern of water is made to answer the purpose of one or rather of two workmen. Bleaching For as two pieces of cloth pass through the rollers at once, were it not for the water, two persons would be required to unfold the cloth, one to each piece.
Plate CVII. fig. 1, exhibits a view of the machine called squeezers, employed to press as much water as possible from the piece after being bleached. It consists of a cast-iron framing, with two wooden rollers, which are pressed together by a double lever, and made to revolve by means of wheels connected with a shaft from a steam-engine or water-wheel. The wet piece is laid down at one side of the machine, and after passing between the rollers, is folded by a workman stationed at the opposite side.
11. The cloth after the squeezing process is still wet, and is crumpled together like a rope. The next process is to pull out each piece to its breadth. This is done by women, a number of whom are constantly employed in this simple but necessary process. But the edges of the piece still continue folded in. To make them straight, a workman knocks them against a smooth beating stock, first one edge and then the other. By this process the pieces are spread out to their full breadth, and all the folds and wrinkles removed as before the bleaching processes commenced. The pieces are then stitched end to end by women with a sailor's needle, to prepare them for the mangle.
12. The next step is mangling the cloth while still wet, by passing it successively between cylinders, forced towards each other by levers, to which a considerable weight is attached. These cylinders require all to be turned quite true, so as to be perfectly round. One of them is of brass, and two are of wood. By this mangling process the water is equalized throughout the whole piece, the threads are flattened, and the cloth stretched, smoothed, and wound upon a roller, and thus rendered fit for receiving the starch.
13. Starching is the next process; and though it be well understood, yet it may not be superfluous to give a short sketch of the processes which the bleacher follows, the great object being to unite economy with exactness. Wheat starch would be too expensive; the bleacher therefore satisfies himself with flour. But the gluten of wheat flour renders it unfit for starching. The first step, therefore, is to get rid of that ingredient. Flour is mixed with water in the proportion of one pound of flour to the gallon of water, and allowed to remain for twenty-four hours. A brisk fermentation takes place, an acid, lactie, is generated, the texture of the gluten is destroyed, and the water acquires a specific gravity of 1·015. After twenty-four hours, the whole liquid is passed through a sieve. The starch passes along with the liquid, but the bran is retained upon the sieve. The starch is then boiled, a little indigo being added, and water also, so as to proportion the thickness of the liquid to the degree of stiffness which the goods are to acquire.
In many cases the starch is mixed with porcelain clay, about equal bulks of flour and porcelain clay being most commonly employed; though the proportion varies according to circumstances. The starch is applied in the state of a pretty thick paste, while the goods are passed between a pair of rollers.
In other cases equal quantities of porcelain clay and calcined sulphate of lime are mixed with the starch. These substances are applied only on one side; but by the rollers they are forced into the cloth, intermix themselves with its internal structure, and add greatly to its apparent strength and thickness. This method of thickening was undoubtedly intended at first as a fraudulent method of making the purchaser believe that the cloth was much Bleaching, stouter and thicker than it really was. But it has been so long practised, and is now so universally known, that all purchasers must be aware of it, and of course not in any danger of being deceived. But it certainly serves the purpose of making the goods appear much more beautiful, and of a stouter fabric to the eye; and as long as they continue unwashed, they are really stronger than they would be without this artificial dressing. So far it is beneficial; and as it does not enhance the price, the purchasers have no reason to complain of imposition.
Plate CVII. fig. 2, represents the starching machine or stiffening mangle; the middle roller being of brass and the other two of wood. They are pressed together by means of levers, which are loaded less or more, so as to leave the requisite quantity of starch in the cloth that passes through the rollers. A is the roll of pieces as they come from the water mangle, B a box containing the starch. It is furnished with a roller fixed near the bottom. The piece, in passing under this roller, gets filled with starch, the superfluous part of which is pressed out again by the rollers of the mangle. The piece is then rolled up as before at the back of the machine.
14. The next process is to dry the goods after starching. This is done by hanging them on rails in an apartment heated by a flue passing round the room and down the centre, where it passes into the chimney. There are usually two furnaces, one at each corner of one of the sides of the apartment. The flues from these furnaces pass round the apartment in the way represented in the margin, and uniting in the centre of the side of the room farthest from the furnaces, pass down in one common flue through the centre of the room to the chimney, which is situated midway between the two furnaces. The side flues are usually covered by thin brickwork, but the middle common flue is covered with plates of cast-iron. When the cloth is hung up in this apartment the temperature is at first low, but it gradually rises as the goods get dry. The workmen, while employed in hanging up the goods on the rails, &c., which occupies a considerable time, find themselves obliged to throw off part of their clothes, and even sometimes to work naked, with the exception of a pair of drawers or a cloth wrapped round their loins.
15. Nothing now remains but the process of calendering, which gives the goods their final gloss and texture. For this purpose they require in the first place to be dampened. This is done by passing them leisurely over a machine, which scatters upon them, as they pass, an infinity of exceedingly small drops. When these drops are first applied, if we hold up the cloth between the eye and the light, we see a great number of small round wet spots, while the greatest part of the cloth is dry. But when the pieces are left for some time standing together in a heap, these spots gradually disappear, and the cloth acquires a uniform dampness, which fits it for assuming the gloss which it acquires by the calendering.
Plate CVIII. fig. 3, represents the damping machine. A is a box containing a circular brush B, which is made to revolve rapidly, its points just touching a surface of water which is kept of a uniform height. The goods, dry from the stove, are laid down at C; they are pulled in single folds over the surface of the box A, by the pair of rollers D, which are turned round by machinery. A shower of minute drops of water is thus thrown up upon the cloth as it moves over the surface of the box, and the piece, folded up by a workman, is left in a heap till the drops have all disappeared, and the cloth acquired a uniform degree of dampness.
Calendering is making the cloth to pass between a pair of rollers forced against each other by the application of a considerable pressure. During this process the texture of the cloth is made to vary at pleasure. When the goods pass simply between the smooth rollers, the threads are flattened, and the whole piece assumes a soft and silky lustre. When two folds of the cloth are made to pass together through the rollers, the threads make an impression on each other, and assume a wiry appearance, with an intermediate hollow between each. Various degrees of this wiry appearance may be given at pleasure.
Plate CVIII. fig. 4, represents the calender. It consists essentially of a frame-work, arranged so as to retain a number of rollers parallel, one above another, with levers and pulleys to press them together, and wheels and shafts to make them revolve. Two of these rollers are of cast-iron, nicely turned and polished, and three (the largest) of wood with iron centres. The piece of cloth, after being dampened, is laid down in front of the calender, and made to pass in various ways between these rollers, after which it is rolled round a cylinder behind, and taken away to be folded.
The goods, after being thus calendered, are folded, and various devices are stamped in red or in blue upon the end of the piece, according to the different markets in which they are to be exposed; for different stamps are requisite for different markets, South America, the West Indies, India, North America, the Mediterranean, &c., requiring each its own device; and, what is very curious, the sale of the goods in a great measure depends upon these stamps; so that if they were absent, the goods, however well prepared, and however excellent in every other respect, would not meet with a ready sale. Everywhere appearances are more attended to than realities. Man is essentially a gullible animal, and quackery is a most important principle in human nature in general. After the goods have been regularly folded, they are placed piece by piece into a Bramah's press, with a sheet of pasteboard between each; and after a certain interval an iron plate is substituted for the pasteboard, to prevent any inequality in the pile. After sufficient pressure in this machine, they are packed up between boards, to prevent any injury during the carriage, and sent to the merchant or manufacturer to whom they belong.
Such is a sketch of the processes at present followed in the most extensive bleaching establishments in Great Britain for bleaching cotton. The processes altogether amount to about twenty-five, and the whole expense of bleaching and finishing a piece of twenty-four yards in length is tenpence, which is somewhat less than one half-penny per yard.
The loss of weight sustained during the bleaching of fine cotton cloth in the bleaching houses round Glasgow amounts very nearly to ten per cent. Of this one half may be considered as weaver's dressing; so that the real loss sustained during the bleaching is not more than five per cent. But when some coarse cotton goods are bleached, we are informed, by a gentleman who tried the experiment, that the loss of weight, independently of the weaver's dressing, amounts to ten per cent.
2.—Bleaching of Linen.
16. From the experiments of Mr Lee, who took out a patent about the year 1810, it appears that the colouring matter of flax is not chemically combined with the fibres. threads constituting the back of the stalk; but that a chemical combination takes place while the plant is steeped in water. The object of this steeping is to rot the plant, and enable the fibres to separate readily from the stalk. It is a putrefaction, which goes on to a considerable extent, and generates so much noxious matter as to destroy the fish, if the flax be steeped in water containing them. This fermentation weakens very considerably the strength of the flax fibres, and even destroys many of them. Mr Lee's process, therefore, if it be practicable on a large scale, would be a prodigious improvement. It would render the flax fibres much stronger, it would increase their quantity, and it would save the expense of the materials employed in bleaching the linen. The writer of this article has been informed that Mr Lee's process has uniformly failed of success when tried in Ireland. If this account be true, it is extremely difficult to explain it. We have seen it performed by workmen under his own direction at Old Bow, near London, with the most complete success; not merely upon handfuls of flax, but upon whole fields of it. Indeed the whole is so extremely simple, that we cannot well see how it should fail, if properly conducted. We cannot, therefore, help suspecting that the prejudices of the Irish, with which it would have to contend, have been too powerful for it; but that, as soon as it shall meet with fair play, it will be found just as practicable, and certainly much cheaper and better than the methods at present in use.
That Mr Lee's process has hitherto failed, and that it has been abandoned by the patentee himself, is an undoubted fact; but we cannot avoid suspecting that this was in some measure the fault of the patentee himself. If, instead of attempting the process at Old Bow, at a distance from the linen manufactory, and where no person qualified to appreciate its importance was likely to be near, he had tried it in a place where the linen manufactory existed, Dundee, for example, or Belfast,—and had he associated with himself some person who was conversant with machinery, and who could have applied a mechanical process more convenient and expeditious than the method of Mr Lee, which was simply beating off the woody fibre by means of wooden mallets,—we cannot but think that the process would have been attended with success. The object of Mr Lee was to save the expense of bleaching linen. For when the flax is separated from the plant without the putrefactive process induced by steeping it in water, nothing more is necessary in order to make it white than simply to wash it in water.
As steeping is uniformly practised, the colouring matter becomes chemically combined with the fibres of the flax, and the process of bleaching must be had recourse to in order to render it white. But we conceive it to be unnecessary to enter into any minute details about the method of bleaching linen, because it is similar to the processes for bleaching cotton. It is much more difficult indeed to bleach linen than cotton; hence the boiling with an alkaline ley, and the steeping in the solution of chloride of lime, must be repeated three or four times. In general, the linen is exposed upon the grass to the sun for some weeks, though this part of the process is not essential. The loss of weight which linen sustains during bleaching amounts to about one third part of the whole weight of the goods. Cotton scarcely sustains a loss of one tenth part. This shows at once the difference in the difficulty between bleaching linen and cotton.
The following experiments, made by Charles Tennant, Esq., of St Rollox, near Glasgow, in July and August 1831, point out the parts of the process in which the loss is sustained, and are so valuable that we cannot avoid inserting them here:
**Experiment 1st.—On bleaching 12 cuts of linen yarn, of the quality of 3 lbs. per spindle, weight 4720 Vam.**
| Operation | Weight of Grain from Bundle | Weight after Drying | Weight Lost | |-----------|-----------------------------|--------------------|------------| | Steeped 36 hours in a solution of 4 gr. caustic soda, at 100° temp., washed, dried, and weighed | 4550 | 170 = 3-69 per cent. | | 1st boil, 6 hours in a solution of 50 gr. caustic soda, at 212° temp., washed, dried, and weighed | 4290 | 260 = 5-71 | | 1st steep, 12 hours in a solution of chloride of lime of 1-005 specific gravity, exhausted | 4290 | 30 = 0-70 | | 1st steep, 3 hours in a solution of sulphuric acid of 1-005 specific gravity | 3640 | 420 = 9-55 | | 2d boil, 3 hours in a solution of 24 gr. caustic soda | 3095 | 35 = 0-90 | | 2d steep, 12 hours in a solution of chloride of lime of 1-004 specific gravity, exhausted 1th | 3095 | 115 = 3-02 | | 3d boil, 4 hours in a solution of sulphuric acid of 1-005 specific gravity | 3570 | 120 = 3-22 | | 3d steep, 3 hours in a solution of 24 gr. caustic soda | 3510 | 50 = 1-40 | | 3d steep, 14 hours in a solution of chloride of lime of 1-005 specific gravity, exhausted 1th | 3432 | 63 = 1-93 | | 4th steep, 14 hours in a solution of sulphuric acid of 1-005 specific gravity | 3410 | 22 = 0-64 | | 4th boil, 3 hours in a solution of 16 gr. caustic soda | 3344 | 66 = 1-93 | | 4th steep, 16 hours in a solution of chloride of lime of 1-004 specific gravity, exhausted 1th, washed, not dried | 3280 | 64 = 2-03 |
Total loss in bleaching to a full white | 35-21 |
**Recapitulation of the above.**
| Loss in drying from the bundle of 4720 gr. | 4550 | 170 = 3-69 per cent. | | Loss in 4 boils 15 hours in solution of 114 gr. caustic soda | 261 = 7-05 | | Loss in 4 steeps 54 hours in solution of chloride of lime of 1-005 specific gravity | 676 = 17-03 | | Loss in 4 steeps 39 hours in solution of sulphuric acid of 1-005 specific gravity | 67 = 1-82 | | Loss in fermenting steep 36 hours in solution of 4 gr. caustic soda, 100° temp. | 260 = 5-71 |
| Total loss | 1434 = 35-21 |
**Experiment 2nd.—On bleaching 12 cuts of linen yarn, of the quality denominated 2 lbs. per spindle, weighing 3460 grains from bundle, and when dried, 3350 110 = 3-18**
| Operation | Weight of Grain from Bundle | Weight after Drying | Weight Lost | |-----------|-----------------------------|--------------------|------------| | Steeped 18 hours in solution of 4 gr. of caustic soda at 100° temp., and washed, not dried | 3350 | 110 = 3-18 | | 1st boil, 6 hours in solution of 38 gr. of caustic soda at 212° temperature | 261 = 7-05 | | 1st steep, 15 hours in solution of chloride of lime of 1-005 specific gravity, exhausted | 676 = 17-03 | | 1st steep, 6 hours in solution of sulphuric acid of 1-010 specific gravity | 67 = 1-82 | | 2d boil, 4 hours in solution of 19 gr. caustic soda | 260 = 5-71 | | 2d steep, 14 hours in solution of chloride of lime of 1-005 specific gravity, exhausted 1th | 260 = 5-71 | | 2d steep, 10 hours in solution of sulphuric acid of 1-010 specific gravity, washed, dried, and weighed | 2360 |
Having lost in all the operations 1100 gr. = 31-79 per cent., including 3-18 of moisture previous to drying. In this experiment the white was fully equal to the former; the materials used were in the same proportion to the weight of yarn, although the time and operations were reduced one half; and this may account also for the saving of the weight of the yarn, 31-79, instead of 35-21, as in the first experiment.
3.—Of Bleaching Wool.
17. Wool, like hair, of which it is a variety, is composed of filaments or tubes filled with a substance of an oily nature. The surrounding surface of these tubes is pierced with an infinite number of small holes which communicate with the internal cavity. It is very little altered by exposure to the air, and undergoes no change from the action of boiling water. It is of great consequence that the bleacher should attend to this circumstance, as will appear immediately.
18. A solution of caustic alkali or caustic ley destroys it altogether, and forms with it a kind of soap.
19. The wool, as it comes into the hands of the manufacturer, usually contains a large portion of the natural greasy matter, from which it must be purified before it can undergo the process of bleaching. Sometimes the farmer cleans it from most of its oil, so as to diminish its weight by fifty or sixty per cent., in order to enhance the value of the article; but care is taken to leave some portion, as the natural fat is found to be the best preservative against the attacks of moths and other insects.
20. The first object then is to carry off the whole of the oily matter, which is called the operation of scouring, and is performed by means of an ammoniacal ley, which is thus prepared. Five parts of river or other soft water are to be mixed with one part of stale purified urine, which is found to contain a large quantity of ammonia. This mixture is to be boiled for a short time; and into this, at about the heat of fifty-six degrees, or so that the hand of the workman can be easily held in it for a considerable time, the wool is to be thrown. Four or five pailfuls will generally be sufficient for twenty pounds of wool. After steeping for a short time, the wool is to be stirred about in the mixture continually for about a quarter of an hour or twenty minutes, according to the quantity of greasy matter. It is then to be taken out and drained into a basket, so that the drainings may drop into the vessel in which it was steeped, that nothing may be lost. It must now be completely rinsed by exposing it in baskets to a continued stream of clear water, while a workman is perpetually employed in stirring it with a pole, till the water passes off perfectly clear. The wool is then removed, and a fresh quantity put into the basket, which is to be treated in the same manner. The steeping and rinsing are to be repeated till the wool has attained as great a degree of whiteness as it is capable of receiving from this operation. It is necessary, in order to conduct this process to the greatest advantage, that the workman should attend to the following circumstances.
21. 1st, A quantity of fresh ley must be from time to time added to the bath, as the immersion of the wool is found to weaken its power; but it is better not entirely to renew the bath, as the grease abstracted from the wool during its immersion forms with the ammonia of the urine a kind of soap, which much increases the cleansing quality of the bath.
22. 2d, Increasing the temperature of the bath will augment its detergent powers, and may sometimes supply the want of an addition of stale urine; but both these circumstances require caution, as too great a degree of heat hardens the greasy matter, and renders it more difficult of solution; and again, too much urine makes the wool harsh.
23. 3d, After being much used the bath becomes too foul, and must be entirely renewed.
24. The wool which has properly undergone the process of scouring should be white, soft, elastic, and open; whereas before it was hard, stiff, and greasy. By this operation the wool loses much more of its weight, so that 100 pounds of raw wool, when completely scoured, will not yield more than 30 or 40 fit for the manufacture of cloth.
25. After scouring, the wool is sometimes carried to the fulling mill, in which it acquires an additional degree of whiteness. The above is chiefly employed for the coarser wools, and wool that has yet to be carded for the making of broad cloth; but for the finer kind it is better to employ a bath in which soap has been dissolved. This method is more expensive, but the expense is compensated by the superior quality of the wool which is thus treated. This operation is performed by the comber, and is thus conducted. The wool is divided into parcels containing each about six pounds and a half. A bath is prepared with two pounds and a half of green or black soap dissolved in a sufficient quantity of boiling water; and in this bath a parcel of the wool is to be washed for a longer or shorter time according to its foulness. It is then wrung by means of a hook, and hung in the sunshine or air to dry. Before it is combed it must undergo a second scouring, which clears it of all the natural oily matter.
26. This quantity of wool is not to be washed all at once, but in successive portions; and fresh hot water is to be added from time to time, in order to free the wool more easily from the grease. For wringing it there is a hook fixed at each end of the washing-tub, on which the wool is fastened and turned round by means of a handle or winch, fixed to one of the hooks. As economy should be consulted in every manufacture, a method of scouring wool without soap would be of considerable advantage. Fullers have long been in the habit of employing a species of clayey earth, called from them fullers' earth, which has the property of combining with the greasy matter, and rendering it more soluble in water. Before the wool is quite dry it is combed, as this operation is found to succeed best when it is a little moist, it being then easier to form it into proper lengths of three or four feet. Considerable nicety is requisite in the conducting of these first processes, as much of the success of the succeeding operations depends on their proper management.
27. After combing, the wool sometimes undergoes two or three further washings, especially when it is required of a very delicate white.
28. It is known that the wool has been properly scoured by its filaments being smooth, long, and slender, white, and perfectly free from foreign substances, and not having lost their natural tenacity. The Dutch wool is generally the purest; the English is next in quality, but is much harsher and fouler. The German wool is still harsher than the English, and the French is inferior to them all.
29. The loss sustained by the wools in scouring is proportional to their impurity. Thus the French and German lose about a third of their weight, while the Dutch and English do not lose above a fourth.
30. But this scouring, whether it be performed with
---
1 The detergent property of urine has been long known, and it is frequently employed in washing to save soap. At sea, where fresh water cannot be spared for the purpose of washing, the sailors are accustomed to scour their foul linens in stale urine, which so far cleanses them that a subsequent rinsing in salt water renders them tolerably pure and sweet. urine, soap, or earth, is seldom sufficient to bring the wool to that brilliant whiteness which is desirable for some manufactures. This is given it by means of the vapour of sulphur, or by steeping it in sulphurous acid, which is called by the manufacturers sulphuring.
31. The usual method of sulphuring goods is to expose them in a very close apartment to the vapour of burning sulphur. The goods are hung on poles so disposed that the vapour can readily pass between the pieces, and when the chamber is filled, a quantity of sulphur placed in very flat and broad dishes is set fire to, and allowed to burn away gradually in the chamber, while every aperture by which the vapour could escape is carefully closed. The acid vapour generated by the combination of the sulphur with the oxygen of the air of the chamber penetrates to every part of the cloth to which it can get access, destroys the colouring matter, and thus completes the bleaching. Every thing is allowed to remain quiet till it is supposed that the effect of the sulphurous vapour has fully taken place, which requires from 6 to 24 hours.
32. The action of the sulphurous vapour leaves a roughness and harshness on the cloth, which are removed by passing it through a bath slightly impregnated with soap.
4. Bleaching of Silk.
33. Silk is a substance possessing some degree of transparency, and is spun by a caterpillar from a matter contained within its body, which has the property of hardening when exposed to the air. The silk-worm is an inhabitant of the southern climates, being originally brought from Asia, and naturalized in the south of Europe about the period of the decline of the Roman empire.
34. The filaments of silk, as left by the silk-worm, are rolled together into a kind of ball or clew, and in their natural, or what is called the raw state, are covered with a yellow varnish or gum, which obscures their lustre, and gives them an unpleasant roughness.
35. Water has no effect on silk at the boiling temperature, and no change is produced on it by alcohol; but alkaline leys, when tolerably strong, attack, and are capable of dissolving it. The yellow varnish is soluble also in alkaline leys, and it may even be separated by long-continued boiling of the silk. When the varnish is thus carried off, the silk is found to have lost about a fourth of its original weight.
36. Two methods are in practice for bleaching silk; the first, in which it is ungummed or deprived of the natural varnish; the second, in which this is retained, in order to give them that stiffness which is required for gauzes, blends, &c.
37. In the first process, the silk is to undergo a scouring similar to what we have described as necessary for depriving wool of the natural oil. For this purpose a quantity of water is put into a boiler over a fire, and for every hundred pounds of silk to be scoured, thirty pounds of very fine soap are dissolved. The solution is generally boiled, but before the silk is put into it, the heat must be lowered to about 90 degrees of Fahrenheit, and at this temperature it must be kept during the process. The silks are to be hung in the liquor in rods or frames, and left till the gum is sufficiently destroyed; care being taken to alter their position now and then, so that every part may be exposed to the action of the bath. When perfectly ungummed, they are flexible and of a dull whiteness; in this state they are to be wrung with the pin to clear them of the soapy water, then well shaken, and put into coarse linen bags, in parcels of from twenty to thirty pounds each.
38. These bags are now to be steeped in a fresh bath, or, as the workmen say, are to be baked. The bath is prepared in a manner and proportion much as before, except that the quantity of soap may be somewhat diminished as the heat is to be increased; for the silk is now to be boiled for two or three hours, taking care to keep the bags from sticking to the bottom of the boiler, by frequently stirring them with a stick.
39. For silk that is intended to be dyed, the former steeping in the lukewarm bath is unnecessary, and the present boiling only is employed, using a greater quantity of soap in proportion to the fineness of the colour. Thus for the ordinary colours, the proportion above laid down, or even less, will suffice; but for the saffranum colours, and the poppy and cherry red, even 50 pounds are sometimes employed to the 100 pounds of silk.
40. After boiling, the silk is wrung as before, and then washed thoroughly in a stream of water; they are then examined, and if it appears they are not sufficiently or not uniformly scoured, they must be submitted to a fresh bath.
41. The white silk usually sold has a bluish shade. This is given it by a bath impregnated with litmus or indigo. This is prepared by dissolving a pound and a half of fine soap in about ninety gallons of water, in which a small quantity of litmus or indigo has been diffused. The bath is heated to about 90 degrees, and the silk is passed through it over rods or reels till it has acquired the requisite shade. Being taken out, it is wrung and dried.
42. From these processes the silk acquires a tolerably clear white, but the highest degree is given to it by the action of the sulphurous acid, either in the state of vapour, as is usually practised, or by immersing it in the liquid acid, according to the method of Mr O'Reilly.
5.—Bleaching of Rags for the Papermaker.
43. The rags to be whitened should be well washed in the engine, and when reduced to what is called half-stuff, the water should be run off, leaving just enough to allow them to be easily turned. While the rags are thus preparing, a solution of the bleaching-powder is to be got ready, by putting the powder into a pitcher or other convenient vessel, and pouring upon it two or three gallons of water, stirring and bruising it well, till everything soluble is taken up. After it has stood some time to allow the insoluble sediment to fall down, it is fit for use, and the pure solution should be poured into the engine. The sediment may be repeatedly washed with fresh portions of water to exhaust any remains of soluble matter, which alone is useful in the whitening process. While this last operation is going on, the engine is to be kept moving, and to continue so for about an hour, which will generally be sufficient to produce the requisite degree of whiteness. The water may now be returned upon the engine, and the washing continued as usual till the process be completed. The quantity of powder usually allowed is from two pounds to four pounds for every hundredweight of rags, in proportion to the whiteness required and the difficulty of whitening the stuff.
Rags containing dyed colours to be discharged, should be well washed, and reduced to half-stuff. They are then removed from the engine and put into a puncheon made water tight, but having a sufficient opening in the side to admit with ease the putting in and taking out of the stuff, and capable of being shut up so as to retain the water. Having put the stuff into this puncheon, take for every hundredweight of the rags a solution containing from five to eight pounds of bleaching powder, according to the strength and fixedness of the colours to be discharged. Pour the solution into the puncheon among the stuff, allowing liquid enough to let the stuff float easily, and for each pound of powder used add half a pound of sulphuric acid. Then shut up and secure the opening so as to make Bled-el-Jereede, a territory in Africa, of considerable extent, immediately to the south of the kingdoms of Algiers and Tunis, from which it is separated by the range of the Atlas. On the southern side it passes gradually into the great desert of the Sahara, the character of which it in some degree partakes. The northern districts indeed are tolerably watered by streams descending from the Atlas, some of which spread even into considerable rivers, that never reach any receptacle, but are either absorbed by the sands or diffused into shallow and extensive lakes. Some of the districts thus irrigated possess a considerable share of fertility; but the greater number labour under severe drought, which always increases till the country assumes the arid character of the great desert. It is only in a few spots that the grains and fruits which are carried to such perfection in Barbary can be raised with advantage. The date, peculiarly adapted to dry soil, is almost the exclusive product, and forests of the tree producing it cover a great extent of the territory. It forms the food of the people, and their chief article of export, by which they obtain the few foreign luxuries in which they indulge. They likewise rear sheep and goats, and employ themselves in the chase of the ostrich for the sake of its valuable feathers, which form another article of trade.
6.—Bleaching of Yellow Wax.
44. Before the discovery of chlorine and its application to bleaching, this was effected by exposing the yellow wax, formed into thin cakes, to the free action of the air, sun, and dews. The chlorine, however, as being far more expeditious, is to be preferred.
In the bleaching of wax it is proper to employ the simple gas, and its action would be the most effectual if used in the gaseous form. For this purpose a pneumatic tub, with a cover secured in the manner recommended by Rupp, is the most proper. This should be filled with water, and the wax, shred very fine, must be introduced, and the gas made to pass through the water, while the agitator is kept in constant motion. In the course of an hour or two the wax will be bleached, may be separated from the water, melted and formed into cakes.
7.—Of Whitening and Cleaning Prints, Maps, Books, and other Articles of Paper.
45. The chlorine was first applied to this purpose by Chaptal, and the method has been employed with the greatest success by Vialard and Heudier.
Gas might be used for this purpose, but it is safer and equally efficacious to employ it in the liquid form.
46. Simple immersion in chlorine, letting the article remain in it a longer or shorter space of time, according to the strength of the liquid, will be sufficient to whiten an engraving. If it be required to whiten the paper of a bound book, as it is necessary that all the leaves should be moistened by the liquid, care must be taken to open the book well, and to make the boards rest on the edge of the vessel, in such a manner that the paper alone be dipped in the liquid; the leaves must be separated from each other, in order that they be equally moistened on both sides.
The liquor assumes a yellow tint, and the paper becomes white in the same proportion. At the end of two or three hours the book may be taken from the acid liquor and plunged into pure water, with the same care and precaution as recommended in regard to the acid liquor, that the water may exactly touch the two surfaces of each leaf. The water must be renewed every hour, to extract the acid remaining in the paper, and to dissipate the disagreeable smell.
47. By following this process there is some danger that the pages will not be all equally whitened, either because the leaves have not been sufficiently separated, or because the liquid has had more action on the front margins than on those near the binding. On this account the practice followed by book-binders, when they wish to whiten printed paper, is to be preferred. They destroy the binding entirely, that they may give to each leaf an equal and perfect immersion; and this is the second process recommended by M. Chaptal.
"They begin," says he, "by unsewing the book and separating it into leaves, which they place in cases formed in a leaden tub, with very thin slips of wood or glass, so that the leaves when laid flat are separated from each other by intervals scarcely sensible. The acid is then poured in, making it fall on the sides of the tub, in order that the leaves may not be deranged by its motion. When the workman judges, by the whiteness of the paper, that it has been sufficiently acted upon by the acid, it is drawn off by a cock at the bottom of the tub, and its place is supplied by clear fresh water, which weakens and carries off the remains of the acid, as well as its strong smell. The leaves are then to be dried, and, after being pressed, may be again bound up.
"The leaves may be placed also vertically in the tub; and this position seems to possess some advantage, as they will then be less liable to be torn. With this view I constructed a wooden frame, which I adjusted to the proper height, according to the size of the leaves which I wished to whiten. This frame supported very thin slips of wood, leaving only the space of half a line between them. I placed two leaves in each of these intervals, and kept them fixed in their place by two small wooden wedges, which I pushed in between the slips. When the paper was whitened I lifted up the frame with the leaves, and plunged them into cold water, to remove the remains of the acid, as well as the smell. This process I prefer to the other.
48. "By this operation books are not only cleaned, but the paper acquires a degree of whiteness superior to what it possessed when first made. The use of this acid is attended also with the valuable advantage of destroying ink spots. This liquor has no action upon spots of oil, or animal grease; but it has been long known, that a weak solution of potash will effectually remove stains of that kind.
49. "When I had to repair prints so torn that they exhibited only scraps pasted upon other paper, I was afraid of losing these fragments in the liquid, because the paste became dissolved. In such cases I inclosed the prints in a cylindrical glass vessel, which I inverted on the water in which I had put the mixture proper for extricating the oxygenated muriatic acid gas. This vapour, by filling the whole inside of the jar, acted upon the print, extracted the grease as well as ink spots, and the fragments remained pasted to the paper."
50. Vialard and Heudier by this process restored several of the most valuable books of the French national library, and we believe they were the first who carried Chaptal's process into actual execution. (L.) The name of the country is commonly supposed to be derived from *jerid*, a date; but Dr Shaw conceives that *jeridé*, dry, is the true etymology.
The people of this district, exposed to the direct rays of a burning sun, are lean and swarthy, with a shrivelled appearance, and their eyes are frequently subject to inflammation, in consequence of the reflection of the rays from a white hard soil; yet the plague, which commits such havoc in the cities of Barbary, never attacks the Bled-el-Je-reede, notwithstanding the constant intercourse between the two places. The inhabitants in general reach a good old age, of which they often exhibit the appearance, without any decay in the faculties of body or mind. They are composed of a mixture of Arabs and native Africans, partly living in rude villages, partly wandering in tents. In some places, where rain scarcely ever falls, the people construct their dwellings of the salt with which the territory abounds; but a casual shower often melts these frail habitations. Another characteristic feature is the occurrence of water, which is almost uniformly found on digging to a certain depth beneath the arid surface, and to which the natives give the appellation of the sea under ground. When the soil is dug into, it rushes forth, sometimes in such quantities as to drown the workmen employed. By bringing up this subterranean store, fertility is communicated to the most barren soils; but the labour of the operation is such that it can be practised only to a limited extent.
**BLEEDING.** See Surgery.
**Bleeding of a Corpse,** a phenomenon superstitiously believed to have been occasionally exhibited by the bodies of persons murdered, which, on the touch, or even the approach of the murderer, began, it was said, to bleed at the nose, ears, and other parts. This circumstance was formerly admitted in England and other parts as a sort of detection of the criminal, and proof of the fact.
**BLEKEDE,** a bailiwick in the province of Luneburg and kingdom of Hanover, taking the name from its capital, a town of 1510 inhabitants on the river Elbe. It extends over 76,420 acres, and contains two towns, 54 villages, with 7460 inhabitants, mostly agriculturists.
**BLEMYES,** or **Blemmyes,** a fabulous people of Ethiopia, said to have had no heads, their eyes and mouths having been situated in their breasts.
**BLENCH** or **BLANCH.** See **BLANCH.**
**BLENDE,** in Mineralogy, the sulphuret of zinc, and by much the most common ore of that metal. In its crystalline form, its colour and appearance, this mineral varies extremely. The most common varieties, certainly, are brown or black, but a fine, oil-green, transparent species occurs at Schemitz in Hungary; another of a rich hyacinth red colour is met with at Klapruck in Transylvania; and a third in botrioidal concretions, having a white fibrous structure, is found near Fowey in Cornwall. The fibrous blende of Prziham in Bohemia possesses, after a fresh fracture, a lustre almost metallic, and is peculiar, from the portion of cadmium with which it is associated. The crystalline form of blende is tessellar, and often presents the faces of the dodecahedron, to which figure the larger cleavable varieties are easily reducible by mechanical division. The surfaces of the crystals are extremely re-
splendent, and have at times a strong adamantine lustre. They yield to the knife, are rather brittle, and possess a specific gravity equal to 4.07. Blende, according to Thomson and Berthier, is composed of
- Zinc: 59.09% - Iron: 12.05% - Sulphur: 28.86%
When strongly heated in the oxidating flame of the blow-pipe, it gives off vapours of zinc, which form a coating on the charcoal; but it does not melt. It is soluble in nitric acid, during which process sulphuretted hydrogen is disengaged. Some varieties are phosphorescent in the dark when rubbed, and present that phenomenon even although the experiment be repeated under water. The sulphuret of zinc occurs both in primitive and secondary rocks, and is an almost constant accompaniment in the veins of lead, iron, and copper, associated with quartz, calcareous spar, or barytes. Great quantities of blende are found in Derbyshire and Cornwall, at Alston Moor and Lead Hills, at Klapruck in Transylvania, and Freyberg in Saxony; in Hungary, Bohemia, Silesia, and the Hartz. It is used in some places for obtaining the zinc in combination with it; but is otherwise an unimportant ore.
**BLENHEIM,** a village of Germany, in the kingdom of Bavaria, situated in long. 2° 30'. E. lat. 48° 40'. N. This village is remarkable for the defeat of the French and Bavarians in 1704, by the English and their confederates under Prince Eugene and the Duke of Marlborough. See **BRITAIN.**
**BLENHEIM House,** a princely mansion erected for the Duke of Marlborough at Woodstock, near Oxford, as a testimony of national gratitude, and, with the manor of Woodstock, settled on the duke and his heirs, in consideration of the eminent services performed by him, and more especially of the decisive victory he had gained at Blenheim over the French forces under Marshal Tallard. The sum of £500,000 was voted by parliament for the purchase of the manor of Woodstock, and the erection of this edifice, which has generally been considered a very heavy monument of public gratitude.
**BLENNY.** See **Ichthyology, Index.**
**BLETCHINGLEY,** a parish and borough in the hundred of Tandridge, in the county of Surrey, twenty miles from London. It is situated on a rising ground at the foot of a range of chalk hills. It has no market. The inhabitants amounted in 1801 to 1344, in 1811 to 1243, and in 1821 to 1187.
**BLETONISM,** a supposed faculty of perceiving and indicating subterraneous springs and currents by means of sensation. The term is derived from a M. Bleton, who for some years excited attention by his being supposed to possess the faculty in question. But the faculty and its possessor are now alike forgotten.
**BLIGHT,** a disease incident to plants, and affecting them variously, the whole plant sometimes perishing by it, and sometimes only the leaves and blossoms, which are scorched and shrivelled up, whilst the rest remains green and flourishing. See **Plants, Diseases of.**
**BLIND,** An epithet applied to a person deprived of the use of sight; or to one from whom light, colours, and all the variety of the visible creation, are intercepted by some natural deprivation or accidental disease.
There is no external sense or faculty which affords such an endless variety of perceptions as that of vision; nor is there any loss that can be sustained productive of so many disadvantages and evils as the want of that faculty. By no avenue of perception is knowledge so accessible, by none, in fact, does it flow so abundantly, as through the channel of this sense, which not only reveals external things in all their beauty, in all their changes, and in all their varie- ties, but supplies those materials out of which the imagination creates new forms still more glorious; whilst the understanding traces the varied relations existing among the ideas thus received, and gives birth to a secondary and reflex class still more subtle and refined. To the blind man, however, the visible universe is totally annihilated; he is perfectly conscious of no space excepting that in which he stands, or to which his extremities can reach. Sound, indeed, gives him some ideas of distant objects; but these ideas are often obscure and indistinct; and although by them the notion of distance in general, or even of some particular distances, may be obtained, yet they never fill the mind with those vast and exalting conceptions of extension which are inspired by ocular perception. For although a clap of thunder or an explosion of ordnance may be distinctly heard after they have traversed an immense region of space, yet when the distance is uncommonly great, it ceases to be indicated by sound; and hence the ideas of extension acquired by hearing are extremely confused and inadequate. But the living and comprehensive eye darts its instantaneous glance over expanded valleys, lofty mountains, sweeping rivers, and vast tracts of land or of ocean. It measures in an instant of time the mighty space from earth to heaven, or from one star to another. By the assistance of telescopes its horizon is almost indefinitely extended, its objects are greatly multiplied, and the sphere of its observation is prodigiously enlarged. By these means the imagination, habituated to vast impressions of distance, can not only recall them in their utmost extent with as much rapidity as they were at first imbibed, but can multiply them, and add one to another, till all boundaries, distances, and measures, are swallowed up in immensity. By profusely irradiating the face of things, and clothing objects in a robe of diversified splendour, nature at once invites the understanding to expatiate on that extensive and gorgeous theatre which she thus opens up, and gratifies the imagination with every possible exhibition of the sublime and the beautiful. The man of sight enjoys these unspeakable advantages, and beholds from afar the objects of his attention and curiosity. Taught by experience, he measures their relative distances; distinguishes their qualities; determines their situations, positions, and attitudes; traverses in security the space which divides them from him; stops at the point where they are placed; and either obtains them with ease, or immediately perceives the means by which the obstacles that intercept his passage to them may be surmounted. The blind, on the contrary, not only may be, but in reality are, during a considerable period, apprehensive of danger from every motion they make towards any object or place, because their contracted power of perception can give them no certain intelligence of the obstacles or hazards which may intervene.
Nor is this the worst of their case. All the various modes of delicate proportion, all the beautiful varieties of light and colours, whether exhibited in the works of nature or of art, are to them irretrievably lost. Dependent for every thing on the good offices of others, and from every object obnoxious to injury, which they are neither capacitated to perceive nor qualified to resist, they are, during the present state of being, rather to be considered as prisoners at large than citizens of nature. The sedentary life to which they are doomed relaxes the frame, and subjects them to all the disagreeable sensations which arise from dejection of spirits. Hence the most feeble exertions create lassitude and uneasiness, and the natural tone of the nervous system, destroyed by inactivity, exasperates and embitters every disagreeable impression. But even from their loss, however oppressive and irretrievable, they derive some advantages; not indeed adequate to recompense, but sufficient to alleviate, their misery. The attention of the mind, confined to those avenues of perception which it can command, is neither dissipated nor confounded by the multiplicity or rapid succession of surrounding objects. Its contemplations are more uniformly fixed upon itself and its own operations; and hence its perceptions of such external things as are contiguous and obvious to observation become more lively and exquisite, whilst even the instruments of corporeal sensation are more assiduously cultivated and improved; so that from them are derived notices and presages of approaching pleasure or impending danger, which entirely escape the attention of those who depend for security on the information of sight. A blind man, when walking swiftly, or running, is kindly and effectually checked by nature from rudely encountering such hard and extended objects as might hurt or bruise him. When he approaches bodies of this kind, he feels the atmosphere more sensibly resist his progress; and in proportion as his motion is accelerated, or his distance from the object diminished, the resistance is increased. He distinguishes the approach of his friend from afar by the sound of his steps, by his manner of breathing, and almost by every audible token which he can exhibit. Prepared for the dangers which he may encounter from the surface of the ground upon which he walks, his step is habitually firm and cautious. Hence he not only avoids those falls which might be occasioned by its less formidable inequalities, but from its general bias he collects some ideas how far his safety is immediately concerned; and although these conjectures may sometimes prove fallacious, yet they are generally so true as to preserve him from accidents not incurred by his own temerity. The rapid torrent and the deep cascade not only warn him to keep a proper distance, but inform him of the direction in which he is moving, and form a kind of audible beacons to regulate his course. In places to which he has been accustomed, he as it were recognises his latitude and longitude from every breath of varied fragrance wafted by the breeze, from every ascent or declivity in the road, from every natural or artificial sound that strikes his ear. Regulated by these and other analogous signs, the blind have not only been known to perform long and difficult journeys themselves, but even to conduct others through dark, tortuous, and dangerous paths, with the utmost security and exactness.
It were endless to recapitulate the various mechanical operations of which they are capable, from the nicety and accuracy of their touch. In some the tactile powers are said to have been so highly improved, as to perceive that texture and disposition of coloured surfaces by which some rays of light are reflected and others absorbed, and in this manner to distinguish colours. But the testimonies to this fact still appear too vague and general to deserve implicit credit. We have known a person who had lost the use of his sight at an early period of infancy, and in the vivacity and delicacy of his sensations was not perhaps inferior to any one; this individual having often heard that others in his situation were capable of distinguishing colours by touch with the utmost exactness and promptitude; and being stimulated partly by curiosity to acquire a new train of ideas, if that acquisition were possible, but still more by incredulity respecting the fact alleged; tried
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1 De comite Mansfeldico coeco referit Keckermannus, solo tactu album a nigro discernere; de equo fusco vel albo, item de columba nigra vel caerulea, judicium ferre potuisse. (Synt. Physic. lib. iii. c. 16.) repeated experiments, by touching the surfaces of different bodies, and examining whether any such diversities could be detected in them as might enable him to distinguish colours—but nothing of the kind was he ever able to ascertain. Sometimes, indeed, he imagined that objects which had no colour, or, in other words, were black, had something different and peculiar in their surfaces; but this experiment did not universally hold; and his scepticism therefore still continued to prevail. That the acoustic perceptions of the blind are distinct and accurate, we may fairly conclude from the rapidity with which they ascertain the acuteness or gravity of different tones, as relative one to another, and from their exact discernment of the various kinds and modifications of sound and of sonorous objects, if the sounds themselves be in any degree significant of their causes.
It is owing to this vivacity and accuracy of the other senses, and the assiduous application of a comprehensive and attentive mind, that we are enabled to account for the rapid and astonishing progress which some of them have made, not only in those departments of literature which were most accessible to their understandings, but even in the most abstract, and, if we may be allowed the expression, occult sciences. What, for instance, can apparently be more remote from the conceptions of a blind man than the abstract relations and properties of space and quantity? Yet the attainments of Dr Saunderson in all the branches of mathematics are well known to the literary world since the publication of his works; and we have the testimony of Dr Guillié to the fact that the blind in general have a remarkable aptitude for the study of the exact sciences.
When we reflect on the numberless advantages derived from the use of sight, and the immense importance of the information it conveys, both for the well-being of the body and the improvement of the mind, we are almost tempted to doubt the fidelity of the reports which have been published concerning such persons as, without the assistance of sight, have arrived at high degrees of eminence even in those sciences which would appear absolutely unattainable without the aid of this sense. It has, however, been demonstrated by Dr Reid, that blind men, by proper instruction, are capable of forming almost every idea, and attaining almost every truth, which can be impressed on the mind through the medium of light and colour, except the sensations of light and colour themselves. (Inquiry into the Human Mind, chap. vi. § 1, 2.) Yet there is one phenomenon of this kind which seems to have escaped the attention of that great philosopher, and of which no author either of this or any former period has been able to offer any satisfactory explanation, although it seems to merit the attention of philosophers. For, admitting that the blind can understand all the phenomena of light and colours, and that on these subjects they may extend their speculations even beyond the sphere of their instructions, and by the mere force of genius and application investigate the mechanical principles of optics from the data which they had previously obtained; yet it will be difficult to assign any reason why these objects should prove more interesting to a blind man than any other abstract truths whatsoever. By means of a retentive memory, it is possible for a blind man to tell that the sky is azure, that the sun, moon, and stars are bright, that the rose is red, the lily white or yellow, and the tulip variegated; by continually hearing these substantives and adjectives joined, he may be mechanically taught to join them in the same manner; but as he never had any sensation of colour, however accurately he may speak of coloured objects, his language must be like that of a parrot, without meaning and without ideas. Homer and Milton had been long acquainted with the visible world before they were afflicted with the calamity of blindness. They might, therefore, still retain the warm and pleasing impressions of what they had seen; their descriptions might be animated with all the enthusiasm which had originally fired their bosoms when the grand or delightful objects which they delineated were immediately beheld; and that enthusiasm might even be heightened by a bitter sense of their loss, and by the regret which a situation so dismal naturally inspired. But how shall we account for the same energy, the same transport of description, exhibited by those on whose minds visible objects were either never impressed, or must have been entirely obliterated?
Yet certain it is, however extraordinary the fact may appear, that the latter class of the blind experience such emotions, and depict them with astonishing accuracy and truth; that they seem to have a kind of imaginative feeling of external beauty, and to enter into accounts of natural scenery with a keener relish than those who enjoy the blessing of sight. To them light, and shadow, and colour in all its variegated modifications, are merely voces et praetera nihil; yet by the force of imagination, aided by the information supplied by the other senses, and by certain suggestions and relations of language, they are enabled, as it were, to approximate to ideas which it is impossible they should ever fully attain, and to form for themselves a set of notions adjusted in such a wonderful manner as to serve as links in the chain of association, and to guide them to the use of accurate expressions, in speaking or writing of things which to them are as if they were not. But the speculations into which these considerations would lead us are of too refined and subtile a nature to be prosecuted further in such an article as the present. Whoever thinks the subject of sufficient consequence to merit a nicer scrutiny, may consult the preface to Blacklock's Poems printed at Edinburgh 1754; or the account of his life and writings by the Rev. Mr Spence, prefixed to a quarto edition of his poems published at London in the year 1756; or the Essai sur l'Instruction des Aveugles, by Dr Guillié, a work which, from the opportunities of observation enjoyed by the author, is naturally of high authority on the subject of which it treats.
It has already been hinted that the blind are objects of compassion, because their sphere of action and observation is abridged; and this is certainly true. For what is human existence in its present state, when deprived of action, and to a certain extent of contemplation? Thus limited, all that remains is the information derived from form, or from sensitive and locomotive powers. But for these, unless directed to happier ends by superior faculties, few rational beings would, in our opinion, be grateful. The most important view, therefore, which can be entertained in the
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1 Si la privation de la vue peut, dans quelques circonstances, devenir un avantage, c'est dans l'étude des mathématiques. Les aveugles ont des dispositions naturelles pour cette science, à laquelle ils se livrent avec un goût décidé. Très-jeunes, ils apprennent facilement les opérations les plus compliquées de l'arithmétique, et, sans employer aucun des moyens dont les clair-voyants font usage pour la géométrie, ils ont une idée exacte et précise des figures; ce qui est prouvé par leur succès dans l'algèbre, la trigonométrie, et les autres branches subséquentes des mathématiques. Leur intelligence pour cette étude est tellement développée, que non seulement ils sont en état de suivre parfaitement les démonstrations faites sur le tableau, et de profiter des leçons publiques données par les maîtres les plus distingués (M. Biot, M. Françoise), mais même remporter, dans les Lycées, les premiers prix sur les clair-voyants. (Essai sur l'Instruction des Aveugles, p. 159, 160.) education of a person deprived of sight, is to redress as effectually as possible the natural disadvantages under which he lies; or, in other words, to enlarge as far as may be the sphere of his knowledge and activity. But this can only be done by the improvement of his intellectual, imaginative, or mechanical powers; and which of these ought to be most assiduously trained and cultivated, the genius of every individual can alone determine. Were men to judge of things by their intrinsic nature, less would be expected from the blind than from others. But, by some pernicious and unaccountable prejudice, people generally hope to find them either possessed of preternatural talents, or more attentive than others to those which they actually do possess: for it was not Rochester's opinion alone,
That if one sense should be suppress'd, It but retires into the rest.
Hence it unluckily happens that blind men, when they do not gratify the extravagant expectations of the spectators, too frequently sink in the general estimation, and appear to be much less considerable and meritorious than they really are. This general diffidence of their powers at once deprives them both of the opportunity and the spirit to exert themselves; and they descend at last to that degree of insignificance in which the public estimate has fixed them. From the original dawning of reason and spirit, therefore, the parents and tutors of the blind ought to inculcate this maxim,—that it is their indispensable duty to excel, and that it is absolutely in their power to attain a high degree of eminence. To impress this notion on their minds, the first objects presented to their observation, and the first methods of improvement applied to their understanding, ought to be capable of being comprehended without difficulty by those internal powers and external senses which they possess. Not that improvement should be rendered quite easy to them, if such a plan were possible; for all difficulties which are not really or apparently insuperable heighten the charms and enhance the value of those acquisitions which they seem to retard. But care should be taken that these difficulties be not magnified or exaggerated by imagination; since the blind have naturally a painful sense of their own incapacity, and consequently a strong propensity to despondency continually working in their minds.
For this reason, parents and relations ought never to be too ready in offering their assistance to the blind in any office which they can perform, or in any acquisition which they can make for themselves, whether they are prompted by amusement or necessity. Let a blind boy be permitted to walk through the neighbourhood without a guide, not only though he should run some hazard, but even though he should suffer some pain. If he have a mechanical turn, let him not be denied the use of edge-tools; for it is better that he should lose a little blood, or even break a bone, than be perpetually confined to the same place, and thus debilitated in his frame, and depressed in his mind. Such a being can have no employment but that of feeling his own weakness, and becoming his own tormenter; or perhaps transferring to others a portion of the malignity and peevishness engendered by the natural, adventitious, or imaginary evils which he feels. Scars, fractures, and dislocations in his body, are trivial misfortunes compared with imbecility, timidity, or fretfulness of mind. Besides the pernicious effects of inactivity in relaxing the nerves, and consequently in depressing the spirits, nothing can be more productive of discontent, envy, jealousy, and every mean and malignant passion, than a painful impression of dependence on others, and of our insufficiency for our own happiness. This impression, which even in his most improved state will be but too deeply felt by every blind man, is redoubled by that utter incapacity of action superinduced by the officious humanity of those who would anticipate or supply all his wants, prevent all his motions, and do or procure every thing for him without his own interposition. It is the course of nature that blind people, as well as others, should survive their parents; and it may likewise happen to them to survive those who, by the ties of blood and nature, are more immediately interested in their happiness. But when they come to be dependent on the world, such exigencies as they themselves cannot meet will be but coldly and languidly supplied by strangers. If their expectations be high, their disappointments will be the more sensible; their desires will often be resisted, seldom fully gratified; and, even when their requests are granted, the concession will sometimes be so ungraceful as to deprive it of the character of kindness. For these reasons, we repeat, that, in the training of a blind man, it is infinitely better to direct than to supersede his own exertions. From the time he can move and feel, let him be taught to supply his own wants; to dress and to feed himself; to run from place to place, either for exercise or in pursuit of his own amusements or avocations.
In these excursions, however, it will be proper for the parent or tutor to superintend his motions at a distance, without seeming to watch over him. A vigilance too apparent may defeat its own object, and create, in a mind naturally jealous, a suspicion of its originating in some interested motive. But, on the other hand, when dangers are obvious and great, those who are intrusted with the care of the blind will find it neither necessary nor expedient to make their vigilance a secret. They ought then to acquaint their pupil that they are present with him, and to interpose for his preservation whenever his temerity renders it necessary. But objects of a nature less noxious, which may give him some pain without any permanent injury or mutilation, may with design be thrown in this way, provided, however, that the design be industriously concealed; for his own experience of their bad effects will prove a much more eloquent and sensible caution than the abstract and frigid counsels of any monitor whatever.
When the season of childish amusement has expired, and the inebriety of animal spirits has abated, the tutor will probably observe, in the whole demeanour of his pupil, a more sensible degree of timidity and precaution, and his activity will then require to be stimulated rather than restrained. In this crisis, exercise will be found requisite to preserve health and facilitate the vital functions, as well as for the mere purpose of recreation; and, of all kinds of exercise, riding on horseback will be found by far the most eligible and advantageous. On such occasions, however, care must be taken that the horses employed be neither capricious nor unmanageable; for on the docility of the animal which he rides, not only the safety, but the confidence, of the blind will entirely depend. In these expeditions, whether long or short, his companion or attendant ought to be constantly with him; and the horse should either be taught to follow its guide, or be conducted by a leading rein. Next to this mode of exercise is walking. If the constitution of the blind boy be tolerably robust, let him be taught to encounter every vicissitude of weather which the human constitution can endure with impunity. And when the cold is so intense, or the elements so tempestuous, as to render air and exercise abroad impracticable, there are methods of exercise within doors, which, though not equally salutary, are still highly eligible. The dumb-bells, the bath-chair or spring board, and the common swing, have been particularly recommended for this purpose; and as each affords an agreeable exerccitation, any of them may be had recourse to at pleasure. But without dilating further in general observations and recommendations, we shall now proceed to give some account of the practical methods employed in developing the physical and intellectual faculties of the blind, and particularly in communicating to them elementary instruction in the ordinary branches of education; and, with this view, we shall endeavour to describe as briefly as possible the system practised in the Asylum for the Industrious Blind in Edinburgh,—an institution which has long been managed with equal judgment and success, and which, although in some respects inferior to that of Paris, is nevertheless upon the whole well calculated to serve as a model for others of a similar description.
This asylum was for many years the only one of the kind in Scotland; but latterly an institution of the same description has been formed at Glasgow, and is now conducted upon nearly the same plan. It was originally intended for men; and, during a period of twenty-eight years from its formation, no provision whatever was made for the employment or instruction of the blind of the other sex, who, from their greater helplessness, have still stronger claims to the charitable and humane consideration of the public. But about the year 1820 a female asylum was instituted under the care of the same directors, though in a separate house; and both branches of this interesting establishment are now conducted upon the same general plan, and with nearly equal success.
The leading feature of this plan is to combine industry with instruction, and alternately to find occupation for the hands and heads of those who are admitted into the asylum. Accordingly, the men and boys are employed in making baskets of all descriptions; in weaving cloth of cotton, linen, and hair; in rope-making in all its branches; in forming matresses of straw, sea-grass, and hair, and in stuffing beds; in working door-mats, hearth-rugs, and other articles of this description; and, in general, in any occupation for which they have a taste, or in which they are likely to excel. The females, on the other hand, are employed in sewing, knitting, spinning, and other occupations peculiar or suited to their sex, especially in the different kinds of "plain and white seam," as it is called, which they execute with singular neatness. Stockings, shoes, snow-boots, table-mats, table-covers, shawls of all descriptions and colours, spencers, tippets, dresses for ladies and gentlemen, hair-mits, and such like articles, are also manufactured in the asylum. A great part of the knitted fancy work has, we understand, been invented by the mistress of the house; and such is the perfection to which this elegant branch of industry has been carried, that its products are said to have found their way to all parts of the world.
France has done much towards the education of the blind, which indeed has engrossed a large share of attention in that country; but although the methods employed are in some respects superior in point of scientific adaptation, it may, nevertheless, be doubted whether any institution in the neighbouring kingdom be upon a more efficient footing than that in Edinburgh, which owes not only its existence, but the success which has attended its endeavours, to the spontaneous and benevolent zeal of enlightened individuals. Various opinions have been expressed respecting the French method of teaching the blind to read by means of letters in relief,—a very ingenious though by no means a recent invention. It has been said, for example, that angular letters are preferable to circular ones, as being more easily felt; and Mr Gall of Edinburgh has constructed an alphabet of this kind on the French plan, whilst others have been making trial of a variety of shapes and forms with a view to the same object. But no device of this kind has hitherto been patronised by the directors of the Edinburgh institution; nor, as far as we know, has any one yet been proposed which is in all respects calculated to answer the end proposed. From what has been done, however, for enabling the blind to feel a written language, it seems practicable, by some analogous method, to teach them both to read and write; and we are inclined to hope that such a method, combining distinctness with simplicity and cheapness, will in time be discovered.
In the Edinburgh institution the men and women are taught to read and write by means of what is called the "string alphabet." This is formed by so knotting a cord, ribbon, or the like, that the protuberances thus made upon it may, by their shape, size, and situation, denote the elements of language. The letters of this alphabet are distributed into seven classes, which are distinguished by certain knots or marks; and each class comprehends four letters, excepting the last, which includes only two. The first or A class is distinguished by a large round knot; the second or E class, by a knot projecting from the line; the third or I class, by a series of links, vulgarly called the "drummer's plait;" the fourth or M class, by a single noose; the fifth or Q class, by a noose with a line drawn through it; the sixth or U class, by a noose with a net-knot cast on it; the seventh or Y class, by a twisted noose. The first letter of each class is denoted by the simple characteristic of its respective class; the second by the characteristic and a common knot close to it; the third by the characteristic and a common knot half an inch from it;
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1 The first attempt of this kind appears to have consisted in a modification of the Illyrian or Slavonian alphabet, which was doubtless preferred on account of the square form of the letters; but on trial it was found to possess no advantage over the common characters, and to have disadvantages peculiar to itself. (Fournier, Manuel Typographique, tome ii. p. 226, No. 68, 1766.) Movable letters on small tablets of wood were next tried; but after a time this expedient was also abandoned, as not suited for the instruction of the blind, though singularly well adapted for teaching children who see to read. In fact, it was by means of similar letters that Usher, afterwards archbishop of Armagh, was taught to read by his two aunts, who were both blind. (Biographia Britannica, ed. Usher; London, 1773.) In the sixteenth century letters were engraved in wood for the instruction of the blind;—these, however, were not in relief, but cut out in the ordinary way of engraving;—the fingers could with difficulty be employed in ascertaining their configuration;—when used in printing, the letters remained white, whilst the rest of the space was blackened;—and hence they had none of the advantages which belong to letters in relief, and which are essential in the instruction of the blind. (Francesco Lucas, Arte de Escribir, Madrid, 1590, etc.) This method was reproduced with some modifications in 1757, by Rampazzetto, an Italian; but with no better success. (Esempio di più sorti di Lettere di M. Gio Francesco Cresci, Milanese, Scrittore en Venetia; 1757, 4to.) In 1640 a writing-master of Paris, called Pierre Moreau, caused movable characters to be cast in lead for the use of the blind; but, discouraged by the difficulties he met with, or not choosing to incur the expense to which the prosecution of the scheme would have subjected him, he abandoned it, and applied himself to the formation of matrices for a new variety of letter, which still bears his name in French typography. A simpler and more ingenious method than any of these consisted in forming letters by means of pins stuck into large punchcards, leaving out only the heads, which of course were easily felt, and rendered the shape of the letters quite distinct as well as palpable, while the arrangement could be altered at pleasure, and with extreme facility. By this natural and easy plan the celebrated Mademoiselle Paradis learned to read. Various other modes were also tried; letters in wood were again had recourse to, and again dropped; and no method secured general approbation till 1763, when letters in relief, that is, letters raised, or as it were embossed on paper, were first invented, and, being gradually improved, were afterwards employed in the instruction of the blind in France. Nor has this invention as yet been superseded by anything that seems better adapted to the purpose. and the fourth by the characteristic and a common knot an inch from it. Thus, A is expressed by a large round knot; B by a large round knot, with a common knot close to it; C by a large round knot, and a common knot half an inch from it; and D by a large round knot, and a common knot an inch from it; and so in the case of the other classes. This alphabet was invented by Robert Milne and David Macbeth, both at one time inmates of the asylum, and it is found by experience to answer the purpose for which it was intended, as by means of it the blind can communicate with their friends and with one another.
Robert Milne, one of the persons above named, also improved the arithmetical board. An instrument of this kind had been invented by Dr Saunderson, and afterwards modified by Dr Moyes; but the board used in the asylum is considered as superior to it in several respects, and has lately undergone a further improvement by the substitution of metal for wood; in consequence of which it has been rendered both cheaper and more correct than before. By means of this instrument both men and women are taught figuring, and may be carried to any extent in arithmetical acquirement. Two small square pins with knobs represent the ten digits.
The blind are taught geography, both ancient and modern, by means of globes and boards constructed solely for their use; astronomy, by means of an orrery and celestial maps similarly adapted; and mathematics, on a board of analogous construction. In all these branches of science the progress they make is considerable, and, with reference to their peculiar situation, astonishing. As the plan of the globes and boards is exceedingly simple, a few words on each will suffice. From a plan submitted to him, the present master constructed two globes, one thirty and the other thirty-six inches in diameter. Having described the meridians and parallels of latitude, and drawn the boundary lines of countries, and divisions of all kinds, he glued on twine or cord on such lines as are continuous, employing shorter pieces to indicate rivers, and pins to denote towns; the portions representing land are covered with fine sand; the rivers and seas are left smooth; the meridian circle, which is of iron, is so deeply marked as to render the divisions easily felt; and the equator is indicated by small pins. The globes, thus prepared and adapted, have been found by experience completely to answer the purposes of instruction. With regard to the maps, again, they are pasted on square boards, and have cord glued on the boundary lines, in precisely the same manner as the globes. The orrery has brass hoops or rings to represent the orbits of the planets, which are indicated by balls or spheres of proper relative dimensions, and slide at pleasure along the rings or orbits; the ecliptic, or the outer edge of the circular board, is marked with the degrees of the circle and the days of the month in such a manner as to be felt; and the signs of the zodiac are raised figures, also placed on the edge. The celestial maps consist of square and oblong boards, on which is glued Bristol paper, cut into the figure of the sign or constellation which it is intended to represent, after which steel knobs of different sizes are driven in to indicate the different magnitudes of the stars, while small knobs on the sides of the board denote the degrees. The mathematical board is a square of fourteen inches, full of small holes, with a few pins fitted to them, so as to represent certain letters of the alphabet; while with fine cord or twine extended from the angular points are formed the lines of the figure or diagram, whatever it may be. The globes and boards for geography, as well as the orrery, celestial maps, and mathematical board, were invented in 1824, and are used in no other institution excepting that of Glasgow, and that of Boston in North America, to each of which a set of these instruments was transmitted by order of the directors of the Edinburgh Asylum. In as far as we are able to judge, these latter instruments seem superior to those employed in the Parisian institution; at all events they are simpler, which is a great advantage; and with regard to the mathematical board, the method of representing the diagrams appears to be by far the best that has yet been employed.
The inmates of this establishment are also taught to play on the violin and piano-forte. They read the music from boards constructed for their use, but by whom invented we have not learned. The game of draughts is a favourite amusement with them. It is played on a board of the common kind, but the alternate squares are covered with sand, and in each there is a small hole fitted to receive a pin, attached to the piece, which is thus retained in the position in which it is placed.
The greater part of the inmates of this institution consists of persons who originally lost their sight by disease or accident; and there are but few who have been blind from their birth. At the same time, it has been remarked that when one child in a family is born blind, those that follow it are also generally born blind. There are two or three instances of this in the asylum; and we know several others without the walls of the institution. This succession of blindness is probably to be referred to the force of imagination; and, in fact, the mother of two blind children being questioned on the subject, stated her belief that the second instance was occasioned by her continually looking on and thinking of her sightless child.
The experience acquired in the institution confirms the general observation which we made at the outset, that the loss of one faculty, especially sight, is almost always accompanied by a compensatory and counterbalancing improvement in the other senses and faculties. This undoubtedly arises, not from any original superiority in the senses or faculties which remain, but from a closer attention to their indications, and above all from incessant application. The sense of touch, in particular, is signalily improved, and, as it were, quickened in blind persons, who have no other means of discovering the size and figure of the bodies presented to them. With regard to the statement, however, which has sometimes been made, that they can distinguish colours by touch, we may mention that no instance of such extreme delicacy of touch has occurred in the experience of the Edinburgh institution. Memory, like touch, is also improved by constant use and application; and this holds equally true in all cases, though it is more signalily exemplified in the case of the blind, who depend so much on this faculty. It has been thought that the memories of the blind are greatly assisted by the exclusion of external objects, which from their multiplicity tend to distract the attention; but as darkness magnifies dangers, which consequently engross the thoughts and excite continual apprehensions, it may reasonably be doubted whether the attention of the blind is
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1 For an account of the method employed in the Royal Institution of Paris, see Dr Guillie's Essai sur l'Instruction des Aveugles, p. 159. In Paris, as in Edinburgh, Saunderson's table has been abandoned as operose and inconvenient. 2 In the Parisian Institution improvement has been carried a step further; fine iron wire covered after the fashion of milliners is used instead of cord for the divisions, as well as the meridians and parallels of latitude; whilst towns and islands are represented by hemispherically-headed nails of different sizes; and over the whole blank paper is pasted, so as in fact to form a skeleton map in relief (Guillie, p. 147, 149.) not at times as liable to be disturbed as that of those who possess the blessing of sight, and receive impressions from the external world; and hence it is to application chiefly that the improvement of this faculty in the case of the blind ought to be ascribed.
The same observation holds true in regard to those signs and indications which persons who see neglect because they are not necessary to be attended to, but which are of great importance to the blind, and are consequently carefully attended to by them. Hence they can discover by the voice whether a person be tall or short, agreeable or disagreeable, and also form some judgment of the passions and affections of the mind. They have even in some cases attempted, from such indications, to describe the external form and beauty of a person. They know the steps of their friends and companions even at a distance. Breathing and smell also afford indications. In hearing a sermon they can tell by the sound of the preacher's voice whether he uses notes; and currents of air, or different modifications of atmospherical pressure, enable them to discover when they approach any object or building. Their curiosity is so intense that at any risk it must be gratified; and as they are often not aware of the danger to which they expose themselves, they generally attain their object. It is a remarkable fact, that a person born blind never dreams that he sees the object of his dreams.
The blind have been made to communicate with the deaf and dumb by means of the finger alphabet; the former, of course, appealing to the sight of the latter, and the latter forming the alphabetical characters palpably on the fingers of the former. An attempt was also made by the deaf and dumb to discover what was said by the blind from the varying configuration of their lips in speaking; but it did not succeed to any extent, and was abandoned, more especially as it could be employed by only one of the parties. In France the means of communication between these two classes of unfortunate have been improved by the invention of a set of pantomimic signs, representing not letters, but words or ideas. These are formed by means of the arms, which being extended somewhat in the manner of a telegraph, are made, by each change of position, to represent a word or idea; and when the blind communicate in this way with the deaf and dumb, their arms are placed in contact, and they go through the strange but ingenious pantomime together in a manner equally grotesque and amusing.
The experience acquired in the Parisian institution is substantially in accordance with what has been stated as the results of continued observation in the Edinburgh asylum. Dr Guillié is decidedly of opinion that the blind have no natural superiority in any sense or faculty over those who possess all their faculties in an ordinary state of perfection. "L'adresse qu'on remarque dans les aveugles pour le toucher," says he, "et l'aptitude des sourds-muets à saisir tous les traits de la physionomie, résultent de la nécessité où ils sont, les uns, de se servir presque continuellement du tact pour suppléer à la vue qui leur manque, et les autres, d'employer la vue pour remplacer l'ouïe et la parole: l'organe n'en est pas moins en tout semblable à celui des clair-voyans; et si l'aveugle-né opéré par Chessel-den ne reconnaisait plus par le toucher, après l'extraction de la cataracte, les objets comme il le faisait auparavant, ce n'est pas qu'il eût perdu, en recevant la vue, la faculté de toucher, mais seulement, parce qu'il ne l'employait pas que comme sens auxiliaire et correctif de la vue." P. 32, 33. In this opinion the Abbé Sicard, Dr Guillié's distinguished colleague, completely coincides.
"The memory of the blind is prodigious." This fact has been exemplified in Paris as well as in Edinburgh and everywhere else; how to account for it is another question. In man there is a memory of sensation and a memory of intelligence: the one recalling his merely physical perceptions; and the other his reflections, judgments, reasonings, speculations, and moral sentiments. Now it is principally with the latter description of memory that the blind are eminently provided; and although they are deprived of the means which persons having the use of sight possess for forming an artificial kind of mnemonics, it is probable that they construct an internal scheme for their own use, and of still superior efficacy. Such at least is the opinion of Dr Guillié; and it appears to be well founded. Helvetius has remarked (De l'Esprit, chap. iii. disc. 3), that a great memory is a phenomenon of order; that it is almost entirely fictitious; and that among men well organised, the great inequality of memory is less the effect of unequal perfection in the organ or faculty which produces it, than of unequal attention in cultivating it. But the blind are in general eminently distinguished for the spirit of order, referred to by the French philosopher as the basis of a great memory; and as the faculty in question depends mainly on association, of which natural arrangement or classification is the very essence, it must of course be greatly strengthened in minds which are animated by the spirit of order, and have a tendency to arrange their ideas in a strictly logical sequence.
Another peculiarity of the blind is great fecundity of imagination; united in some with a facility in analyzing and recombining their ideas, to which their extraordinary progress in the exact sciences is to be ascribed. Of the former quality, Homer, Milton, Delille, and many others might be cited as examples; of the latter we shall give two instances in the words of Dr Guillié. "Le premier est Paingeon, qui, par l'esprit de l'ordre dont il est doué, a acquis des connaissances transcendantes en mathématiques, et après avoir remporté, en 1806, tous les premiers prix au concours général des quatre Lycées de Paris, fut nommé, par le Grand Maître de l'Université, professeur de mathématiques au Lycée d'Angers: l'autre est J. Delille, aujourd'hui pensionnaire des Quinze-Vingts, qui a porté très-loin la métaphysique de la langage Française; un aplomb parfait, une précision admirable dans ses définitions, caractérisent surtout ce sujet que nous nous énorguillissions d'avoir formé." Both were educated under Dr Guillié, at the Royal Institution for the instruction of the blind.
On the subject of the moral condition of the blind Dr Guillié has stated many curious and interesting particulars. They are generally deficient in modesty or shame. "La pudeur, qui est une des grâces de la jeunesse, est presque pour eux un être imaginaire, quoiqu'ils aient une sorte de timidité qui tient peut-être plus, il est vrai, de crainte que de la honte, mais qui augmente beaucoup leur embarras dans certaines circonstances." They are, it is said, for the most part without sensibility and without gratitude; irritable, suspicious, vindictive, implacable. Their situation obliges them to be on their guard against all the world; the consciousness of their own deficiency, and the disadvantages under which it places them, render them suspicious as well as selfish; and, by an easy, and we had almost said natural transition, they come to arrange in the same category their benefactors and their enemies. "Commes de toutes les démonstrations extérieures, qui réveillent en nous la commiseration et les idées de la douleur, les aveugles ne sont affectés que par la plainte," says Diderot, "je les soupçonne, en général, d'inhumanité. Quelle différence y a-t-il, pour un aveugle, entre un homme qui urine et un homme qui, sans se plaindre, verse son sang? Nous-mêmes, ne cessons-nous pas de compatir, lorsque la distance, ou la petite-tes des objets, produit sur nous le même effet que la privation de la vue chez les aveugles." (Lettres sur les Aveugles.) This is too strongly stated; but the principle in human nature, on which the striking observation of Diderot is founded, would lead us to anticipate, at least in part, the moral results to which we have alluded. It has been alleged that the blind have a tendency towards atheism; but this is denied by Dr Guillié, who, however, qualifies his contradiction by a very lamentable admission: "Néanmoins, je ne les justifierai pas entièrement du reproche d'impéteté qu'on leur a fait avec quelque fondement;" and he adds, "la conscience enfin n'a pas sur leurs actions l'influence qu'elle a sur nous." But as these observations are grounded on a partial experience, we hope they have no application to the blind of this country, amongst whom sounder principles and better feelings will always, we trust, prevail; nor will they ever lose a sense of dependence on that Being, whose existence they have only to stretch forth their hands to discover, and who has opened the eye of humanity to compassionate, and the hand of charity to relieve, their wants.
History has preserved sundry particulars of blind persons, who, of themselves, acquired great knowledge before there existed any regular method of instruction applicable to their case. The number of these is considerable; so much so, indeed, that any accurate enumeration would not only be a task of great difficulty in itself, but would also far exceed the limits prescribed to this article. It may not be uninteresting, however, to signalize a few of those who have made the greatest figure in science and in art.
The number of blind appears to have been very considerable in Asia and Italy in the time of the Romans. This is proved by the great number of physicians who at the epoch in question wrote on ocular diseases; but what mode of instruction, or whether any at all, was employed in those times, we have not learned. Diogenes Laertius and Thrasyllus relate (Diog. Laert. lib. ix., Vossius, De Philosophia) that several philosophers voluntarily deprived themselves of sight in order to pursue their contemplations with less interruption; and, amongst those who inflicted on themselves this deprivation, is cited Democritus of Abdera. But it is scarcely probable that this philosopher, the companion of the gymnosophists of India, a man who laughed at every thing, and whom his countrymen wished Hippocrates to cure of madness, because he believed that all things were as they ought to be, depending on chance and the fortuitous aggregations of atoms, should have put out his eyes in order to scoff philosophically, when he might have indulged his humour to so much better purpose with the use of his sight. Besides, putting out the eyes was next to crucifixion, one of the most ignominious punishments inflicted by the laws of ancient times, and as such was reserved only for great criminals. It may therefore be doubted whether the laughing philosopher of Abdera would, on a mere hypothesis, treat himself like a felon; and the words of Cicero, "Democritus impeditri etiam animi aciem aspectu oculorum arbitrabatur" (Tuscult. Disp. v. 39), which have been often quoted, seem rather to express a general opinion than to state a particular fact, or warrant the inference that the philosopher had deprived himself of sight because he thought that the penetration of the mental was impeded by the vision of the natural eye.
Diodatus, Cicero's master in philosophy, applied himself to study with more assiduity than ever, after he had lost his sight; and, what is still more remarkable, he taught geometry with so much precision, that his disciples found no difficulty in comprehending how to trace the most complicated figures from his instructions. (Cicero, ubi supra; Zahn, Specul. Physico-Math. Hist. tome iii. c. 6.) Cornelius Aufidius, a Roman citizen, who had lost his sight in his youth, distinguished himself in the study of elegant literature, and wrote a Greek history. (Zahn, Sens. Ext. Mirab. § 2.) Eusebius the Asiatic became blind at five years of age. He acquired vast knowledge and profound erudition, and taught with the utmost facility as well as success. (Cassiodorus De Inst. Dir. Litter. c. 5.) St Jerome has left an account of Dydimus of Alexandria, his master, of whom he speaks with great respect. This blind man, who had lost his sight at the same age with Eusebius, flourished in the fourth century. Rufinus, Paladius, Isidorus, and several other celebrated men, were his disciples. He acquired great knowledge by having the sacred and profane authors read to him; he was one of the ablest mathematicians of his time; and he applied himself especially to theology, for which he had a decided taste. He composed several works, the principal of which is A Treatise on the Holy Spirit, translated into Latin by St Jerome. Dydimus was pious as well as learned; nevertheless, his attachment to the opinions of Origen, on whose books he had commented, caused his works to be condemned after his death by the council of Lateran. St Athanasius and St Antony had the greatest esteem for him. Dydimus died a.d. 398, at the age of eighty-five. (Hieronymus De Veris Illustr. c. 109; Socrates, lib. iv. c. 25; Rufinus, lib. ii. c. 7.)
Nicease of Malignes flourished in the fifteenth century, and enjoyed great reputation for the extent of his learning. Blind from the age of three years, he nevertheless made great advances in science, and taught publicly, in the university of Cologne, both the civil and canon law, citing from memory long passages which he had never seen, quos numquam videreat. Having been elected doctor of Louvain, the pope granted a dispensation for his admission to priests' orders; after which he employed the rest of his life in preaching, and died at Cologne in 1492. (Bibliothèque des Écrivains des Pays-Bas.)
James Shegkius, born at Schorndorf, in the duchy of Württemburg, taught philosophy and medicine with great success at Tubingen for about thirteen years. Having early become blind, he was so little sensible of the loss of sight that he refused to allow himself to be touched by an oculist, who offered to restore vision—in order, as he said, not to be obliged to see many things which appeared odious or ridiculous. He died at Tubingen in 1587, leaving several treatises on different points of philosophy, medicine, and controversy. (Zahn, Visus Im. Dep. et Cecit. Ex. Mir. p. 114.) John Fernaud, born in Belgium, was the son of a Spaniard, and blind from his birth. His father was very poor; but he surmounted the obstacles both of poverty and blindness, and became a poet, logician, philosopher, and musician. He composed from memory several pieces, which are considered excellent of their kind. (Zahn, ad supra.) Ascanius Pedianus the historian lived several years after the loss of his sight, and wrote treatises on grammar, which exhibit no trace either of his age or infirmity. (Fulgosus, lib. viii. c. 7.)
Uldaric Schomberg, born in Germany towards the commencement of the seventeenth century, lost his sight by the small-pox at the age of three; but as he grew up he applied himself to the study of the belles-lettres, which he afterwards professed with credit at Altorf, at Leipzig, and at Hamburg. (C. Harknocks, Alt und Neu Preussen, 1684.) Bourchenu de Valbonais, born at Grenoble in 1651, became blind when very young, soon after the naval combat at Solbeyne, where he had been present. But this accident did not prevent him from publishing the History of Dauphiné, in two volumes folio. He had made profound researches into the history of his province, and, besides the work just mentioned, published a Nobiliaire de Dauphiné. (Feller, vol. ii.) Of Dr Nicolas Saunderson, Lucasian Professor of Mathematics in the University of Cambridge, and one of the most remarkable men of his time; some account will be found under the proper head. He was born in 1682, at a small town in the county of York, and died at Cambridge in 1739, at the age of fifty-six. He invented a table, which has since been greatly improved, for teaching arithmetic palpably to the blind. A notice of Dr Blacklock will be found under the biography of that individual. Dr Henry Moyes professed the Newtonian philosophy, which he taught with considerable success as an itinerant lecturer. He was also a good chemist, a respectable mathematician, and a tolerable musician.
M. Phefel of Colmar, who lost his sight when very young, in consequence of a violent ophthalmia, composed a great deal of poetry (6 vols. 8vo., Colmar, 1791), consisting chiefly of fables, some of which have been translated into French by M. Degerando. He was privy counsellor to the margrave of Baden; and established at Colmar a military school or academy, where children of the best families were sent to be educated. Among the pupils of this learned blind man may be mentioned Prince Schwartzenberg, Prince Eisenburg, and M. Heilman, lately pensionary of the Quinze-Vingts. He died at Colmar in 1809. Weissemburg of Mannheim became blind at the age of seven. He wrote perfectly, and read with characters which he had imagined for his own use. He was an excellent geographer, and composed maps and globes, which he employed both in studying and teaching this science. He was the inventor of an arithmetical table, differing but little from that of Saunderson. (Journal de Paris, April, 1784.)
The blind man of Puisieux must be known to all who have read Diderot's celebrated Lettres sur les Aveugles. He was the son of a professor of philosophy in the university of Paris, and he had attended with advantage courses of chemistry and botany at the Jardin du Roi. After having dissipated a part of his fortune he retired to Puisieux, where he established a distillery, the products of which he came regularly once a year to Paris to dispose of. There was originality in every thing that he did. His custom was to sleep during the day, and to rise in the evening; he worked all night; "because," as he himself said, "he was not then disturbed by anybody." His wife, when she rose in the morning, used to find every thing perfectly arranged. He spoke very sensibly of the qualities and defects of the organ in which he was deficient, and answered questions put to him with much justness and discrimination. Being interrogated as to the idea he formed of a mirror, he replied, "C'est une machine qui met les choses en relief loin d'elles-mêmes, si elles se trouvent placées convenablement par rapport à elle. C'est comme ma main qu'il ne faut pas que je pose à côté d'un objet pour le sentir." To Diderot, who visited him at Puisieux, he put some very singular questions on the transparency of glass, colours, and such like matters. He asked if naturalists were the only persons who saw with the microscope, and if astronomers were the only persons who saw with the telescope; if the machine which magnified objects was greater than that which diminished them; if that which brought them near was shorter than that which removed them to a distance. He believed that astronomers had eyes of different conformation from those of other men, and that a man could not devote himself to the study of a particular science without having eyes specially adapted for the purpose. "The eye," said he, "is an organ upon which the air ought to produce the same effect as my cane does upon my hand." He possessed the memory of sounds to a surprising degree, and recognised by the voice those whom he had only heard speak once. He could tell if he was in a thoroughfare or in a cul-de-sac, in a large or in a small place. He estimated the proximity of fire by the degree of heat; the comparative fulness of vessels by the sound of the liquor in falling; and the neighbourhood of bodies by the action of the air on his face. Being asked on one occasion if he would not be very well pleased to have eyes, he replied, "Si la curiosité ne me dominait pas, j'aimerais bien autant avoir de longs bras: il me semble que mes mains m'instruirait mieux de ce qui se passe dans la lune que vos yeux ou vos telescopes; et puis les yeux cessent plutôt de voir que les mains de toucher. Il vaudrait donc bien autant qu'on perfectionnât en moi l'organe que j'ai, que de m'accorder celui qui me manque." He employed characters in relief in order to teach his son to read, and the latter never had any other master than his father.
M. Huber of Geneva, an excellent naturalist, and author of the best treatise extant on bees and ants, was blind from his earliest infancy. In reading the descriptions of these insects, we can scarcely persuade ourselves that they are not the production of a singularly clear-sighted man, well versed in this branch of natural history. In executing his great work, however, M. Huber had no other assistance than what he derived from his domestic, who mentioned to him the colour of the insects; and then he ascertained their form and size by touch, with the same facility as he would have recognised them by their humming when flying in the air. This laborious writer has also published a valuable work on education.
Francis Lesueur, born of very poor parents, at Lyons, on the 5th of August 1766, lost his sight when only six weeks old. He went to Paris in 1778, and was begging at the gate of a church, when M. Haüy, discovering in the young mendicant some inclination to study, received him, and undertook the task of instructing him, at the same time promising him a sum equal to that which he had collected in alms. Lesueur began to study in October 1784. Six months after, he was able to read, to compose with characters in relief, to print; and in less than two years he had learned the French language, geography, and music, which he understood very well. His intelligence and penetration were indeed surprising, and he was among the blind what Massieu has since been among the deaf and dumb. He was successively repeater to his comrades, head of the printing and economy of the institution for the blind, and pensionary of the Quinze-Vingts. It is painful to add, that he proved unthankful to his benefactor and master, to whom he owed everything; and that by his conduct he merited the reproach of ingratitude, a vice which, with some reason, has been charged against the blind generally.
Avisse, born at Paris, was one of the most distinguished élèves of the institution. His father, who kept furnished lodgings in the Rue Guénégaud, intended him for the sea; and he embarked when very young on board a vessel fitted out for the slave-trade, in the capacity of secretary or clerk to the captain; but he was struck by a coup de vent on the coast of Africa, and lost his sight from the violent inflammation which ensued. On his return his parents procured his admission into the institution for the blind, where, in a few years, he became professor of grammar and logic. He produced a comedy in verse, in one act, entitled La Ruse d'Aveugle, which was performed on the 2d Nivose, year 5; a scene, also in verse, entitled L'Atelier des Aveugles-travaillleurs; and several other pieces, which were all printed in one volume 12mo, in the year 1803. He died before he had completed his thirty-first year, at the very time when the high hopes entertained of him were on the point of being realized.
Nor have the blind been less distinguished in the practice of the arts than in science and literature. Many instances of their eminence in this respect may be mentioned. Indeed, the want of sight seems little or no impediment to manual dexterity. Stengel mentions a young cabinet-maker of Ingolstadt, who, having lost his sight by an explosion of gun-powder, amused himself by constructing pepper-mills, which he made without the use of any other instrument than a common knife, and executed with so much exactness and elegance that they were thought deserving of a place in the gallery of curiosities at Munich, where they may still be seen. (Laurentius Stengelius De Monstria, c. 16.) Sir Kenelm Digby has stated several extraordinary particulars of a preceptor of his son, who was so completely blind that he could not distinguish the light of noonday from midnight. He surpassed in skill the ablest players at chess; at long distances he shot arrows with such precision as almost never to miss the mark; he constantly went abroad without a guide, and frequented most of the public promenades; he regularly took his place at table, and ate with such dexterity that it was impossible to perceive he was blind: when any one spoke to him for the first time, he was able to tell with certainty his stature and the form of his body; and when his pupils recited in his presence, he knew in what situation and attitude they were. (Digheus De Nat. Corpor. c. 28.) Aldovrandus mentions (Hist. Monstr.) a butcher of Boulogne, who estimated by touch the weight of the animal he was about to kill. M. de Piles saw in Italy a blind man, a native of Cambassy in Tuscany, who was a very good designer. M. de Piles met him in the Justiniani Palace, where he was modelling in wax a statue of Minerva. By means of touch, he had seized with precision the form and proportions of the original. The duke of Bracciano, who had seen him working, doubted whether he was completely blind; and, in order to put the matter to the test, he caused the artist to take his portrait in a dark cave. It proved a striking likeness. Some, however, objecting that the duke's beard, which was of patriarchal amplitude, had helped the artist to recognise him, the latter offered to execute a portrait of one of the duke's daughters, which he accordingly did, and it also proved an excellent likeness. "J'ai vu," says M. de Piles, "sortir des mains de cet illustre aveugle les portraits du feu roi d'Angleterre, Charles I., celui du pape Urbain VIII., et en France, le portrait de M. Hesselin, tous parfaitement exécutés." (Cours de Peinture, p. 260, 1766.) "Nous avons vu, dès nos jours," says Dr. Guilié, to whom we are indebted for the particulars of the more distinguished blind, "M. Buret, l'un des plus habiles sculpteurs de l'académie, devenu aveugle, à l'âge de vingt-cinq ans, par suite de la petite vérole, ne pas cesser pour cela de travailler, comme le faisait l'aveugle de Cambassy." (Essai sur l'Instruction des Aveugles, p. 94, Paris, 1817.)
Giovanni Gambasio of Volterra lost his sight at the age of twenty, and remained ten years in this state, ignorant of even the elements of sculpture. All of a sudden, however, "the desire of making a statue came upon him;" and having handled in every way a marble figure representing Cosmo de' Medici, he formed one of clay, so extremely like that it astonished all who saw it. His talent for statuary now developed itself to such a degree, that Prince Ferdinand, grand duke of Tuscany, sent him to Rome to model the statue of pope Urban VIII., which he also rendered a striking likeness of the original. He afterwards executed many others with equal success. (Aldovrandus, Hist. Monstr.) A Dutch organist, blind from his early youth, became very skilful in his profession; he also acquired the habit of distinguishing by touch the different kinds of money, and even, it is said, the primary colours. He was a first-rate card-player; for in dealing he knew the cards which he gave to others as well as those which he kept for himself. (Lecat, Traité des Sens, p. 11.) Chauvet, born blind, was for several years organist of Notre-Dame-de-Bonne-Nouvelle at Paris. Mademoiselle Paradis of Vienna, who had lost her sight when two years old, formed the delight of the spiritual concerts at Paris in the year 1784. This lady, who had great talents for musical composition, invented a method of writing whatever she composed, by figuring the concords. She began at first by tracing them on cards pricked with needles; but this first essay proving unsatisfactory, she fell upon another method, which, however, has not been explained,—a circumstance we regret the more, since it has been described as at once certain and of easy execution. Holman, the blind traveller, being still alive, can scarcely with propriety be made the subject of a notice in this place.
This catalogue might easily be extended; but enough has been said, and a sufficient number of facts accumulated, to show what the blind are really capable of. There seems, in truth, to be a sort of compensating power, alike subtle in its resources, and refined in its operation, by which a multitude of latent faculties and unheeded perceptions are called into activity to supply the want of one great inlet of knowledge, and which, taken in the aggregate, and fully developed, appear almost sufficient to fill up the blank which has been left by nature or produced by disease in the catalogue of human organs. Hence there are few things practicable by persons possessed of sight which have not been done by those who want it: whilst in regard to several the balance of advantage is clearly in favour of the blind. This is at once a wise and benevolent provision of nature; in perfect harmony with the whole economy of providence in the structure of the body as well as of the mind of man; and singularly illustrative of that foresight which has provided, with such benevolent care, for the casualties as well as the wants to which we are exposed in the present state of existence. Had the case been otherwise every loss would have been irreparable, and the smallest deprivation would have driven us to despair.
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**Blind Coal**, or **Anthracite**, corresponds to the glance coal of England, and the stone coal of Wales. It is very common in Scotland, and is sufficiently abundant in Ireland. Being less frequent, and of more difficult inflammability, than the common coal, it is both of minor value and of less utility. It is, however, employed in burning lime, in iron founderies, and in smelting works. See Coal.
**Blinding**, a species of corporal punishment anciently inflicted on thieves, adulterers, perjurers, and others, and from which the ancient Christians were not exempt. Sometimes a mixture of lime and vinegar, or merely scalding vinegar, was poured into the eyes till their balls were consumed; sometimes a rope was twisted round the head till the eyes started out. In the middle ages, the punishment of destroying or putting out the eyes was exchanged for that of irrevocably injuring or impairing the sight; which was effected by holding a red-hot iron dish or bason before the eyes till their humours were dried up and their coats shrivelled.
**Blindness**, a privation of the sense of sight, arising from a want of the organs of vision, or an involuntary obstruction of their functions. See Blind.
**Total Blindness** is that state in which all sight or perception even of light is wanting, as in the case of those who are said to be stone-blind. Partial Blindness is that state in which some faint glimmering of sight is left, as is the case with those who have ripe cataracts, and who are never so blind but they can discover day from night.
Perpetual Blindness is that which remains alike under all the diversity of seasons, times, and ages.
Transient Blindness is that which in due time gives way of itself; as that of whelps, which continues for several days, sometimes nine, rarely twelve, after they are littered. The Nogais Tartars, according to Father Duban the Jesuit, who lived amongst them, are born blind, and open not their eyes till several days after birth.
Periodical Blindness is that which comes and goes by turns, according to the season of the moon, the time of day, and the like.
Diurnal Blindness is called hemeralopia.
Nocturnal Blindness, called also nyctalopia, is that which ensues on the setting of the sun in persons who see perfectly in the day, but become quite blind as night approaches. (See Phil. Trans. No. 159, p. 560; and a singular case related by Dr Samuel Pye in the Medical Observ. and Inquir. vol. i. p. 111.)
Blindness in horses. See Farriery.