in general, an appellation given to things greatly inferior in size to that which is usual in their several kinds. Thus there are dwarfs of the human species, dwarf dogs, dwarf trees, and the like.
The Romans were passionately fond of dwarfs, whom they called mani or manco, insomuch that they often used artificial methods to prevent the growth of boys designed for dwarfs, by inclosing them in boxes, or by the use of tight bandages. Augustus's niece, Julia, was extremely fond of a dwarf called Sonopas, who was only two feet and a handbreadth in height. We have many other accounts of human dwarfs, but most of them deformed in some way or other, besides the smallness of their size. Many relations concerning dwarfs we must necessarily look upon as not less fabulous than those concerning giants. The following history, however, which there is reason to regard as authentic, is too remarkable not to be acceptable to the generality of our readers.
Jeffery Hudson, the famous English dwarf, was born at Oakham, in Rutlandshire, in 1619; and about the age of seven or eight, being then but eighteen inches high, he was retained in the service of the Duke of Buckingham, who resided at Burleigh-on-the-Hill. Soon after the marriage of Charles I, the king and queen being entertained at Burleigh, little Jeffery was served up at table in a cold pie, and presented by the duchess to the queen, who kept him as her dwarf. From seven years of age till thirty he never grew taller; but after thirty he shot up to three feet nine inches, and there remained fixed. Jeffery became a considerable part of the entertainment of the court. Sir William Davenant wrote a poem called Jeffreidos, on a battle between him and a turkey-cock; and in 1638 was published a very small book, called the New Year's Gift, presented at court by the Lady Parvula to the Lord Minimus, commonly called Little Jeffery, her majesty's servant, written by Microphilus, with a little print of Jeffery prefixed. Before this period Jeffery was employed on a negotiation of great importance; he was sent to France to fetch a midwife for the queen; and on his return with this gentleman and her majesty's dancing-master, and many rich presents to the queen from her mother Mary de' Medici, he was taken by the Dunkirkers. Jeffery, being thus made of consequence, began to think himself really an important personage. He had borne with little temper the teasing of the courtiers and domestics, and had many squabbles with the king's gigantic porter. At last, being provoked by Mr Crofts, a young gentleman of family, a challenge ensued; and Mr Crofts coming to the rendezvous armed only with a squirt, the little creature was so enraged that a real duel ensued; and the appointment being on horseback with pistols, to put them more on a level, Jeffery, with the first fire, shot his antagonist dead. This happened in France, whither he had attended his mistress in the troubles. He was again taken prisoner by a Turkish rover, and sold into Barbary. But he probably did not remain long in slavery; for at the beginning of the civil war he was made a captain in the royal army, and in 1644 attended the queen to France, where he remained till the Restoration. At last, upon suspicion of his being concerned in the Popish plot, he was seized in 1682, and confined in the Gatehouse, Westminster, where he ended his life, in the sixty-third year of his age. This little hero cuts a considerable figure in Sir Walter Scott's novel of Perceval of the Peak.
In the Memoirs of the Royal Academy of Sciences, a relation is given by the Count de Tressau, of a dwarf called Bebe, kept by Stanislaus, king of Poland, and who died in 1764, at the age of twenty-three, when he measured only thirty-two inches. At the time of his birth he measured only between eight and nine inches. Diminutive as were his dimensions, his reasoning faculties were not less scanty, appearing indeed not to have been superior to those of a well-taught pointer. But that the size and strength of the intellectual powers are not affected by the diminutiveness or tenuity of the corporeal organs, is evident from a still more striking instance of littleness, given us by the same nobleman, in the person of M. Borulawski, a Polish gentleman, whom he saw at Luneville, and who at the age of twenty-two measured only twenty-eight inches. This miniature of a man, considering him only with reference to his bodily dimensions, appeared a giant with regard to his mental powers and attainments. He is described by the count as possessing all the graces of wit, united with a sound judgment and an excellent memory; so that we may with justice say of M. Borulawski, in the words of Seneca, and nearly in the order in which he has used them, posse ingenium fortissimum ac beatissimum sub quolibet corpuculo latere. DYEING
Is the art of communicating a new and permanent colour to any substance whatever; but it is usually confined to the art of giving colours to wool, silk, feathers, cotton, or flax, or the thread or cloth formed of any of these substances. To this more limited signification we shall restrict ourselves in the following treatise. For dyeing or staining paper, wood, bone, leather, marble, &c., the reader is referred to these articles. We shall divide this article into six chapters. In the first we shall give a rapid sketch of the history of the art; in the second we shall treat of the nature and properties of wool, feathers, silk, cotton, and flax, of which the fabrics to be dyed are composed; in the third chapter we shall treat of mordants, or the substances by means of which the colours are fixed on the cloth or thread. The fourth chapter will be occupied with the mode of dyeing the simple colours, or red, yellow, blue, black, and brown. The object of the fifth chapter will be the compound colours, or the different shades of green, purple, orange, and gray. The sixth chapter will be occupied with a sketch of the processes of calico printing. Our object will be to give a general view of the processes, and to explain the theory of dyeing, so far as the present state of our knowledge enables us to go. We shall avoid minute details, except when they may be necessary for understanding the nature of the processes.
CHAPTER I.
HISTORY OF DYEING.
Nature has implanted in man a sense of pleasure which he derives from beholding lively colours properly displayed and contrasted. And this sense receives ample gratification from the gay plumage of the feathered tribes, and the endless variety displayed in the blossoms of the vegetable kingdom. The diversity in the colours of flowers must have early attracted the attention of man, and he could scarcely avoid feeling a desire to employ them to adorn his person; but their fading nature fitted them only for a temporary ornament. It would naturally occur to attempt to transfer some of the most lively colours of the vegetable kingdom either to the skin of the naked savage, or to the different articles of dress with which he covered himself up from the cold, or with which he decorated his person.
A few trials would speedily show that the gay colours of most flowers could not be transferred to any article of dress, at least without a great diminution of their splendour; but a considerable difference would be observed depending upon the colour of the flower. The red flowers would either lose their colour altogether, as they would communicate to cloth, not a red, but a blue colour. The yellow coloured berries, on the other hand, would be found in some instances to communicate a very lively and beautiful, though not a permanent colour.
By multiplying trials, various roots, barks, and fruits would be found capable of communicating certain colours to cloth. These facts would be treasured up, and thus a beginning would be made of the art of dyeing. Accordingly we find this art practised to a greater or smaller extent in the most remote ages, and among the most savage and barbarous nations. Even the lowest of the American tribes, in point of civilization, understood how to communicate several very fine colours, and considerable improvements in dyeing were borrowed from the Americans.
It would be in vain, therefore, to attempt to discover Produced to whom the art of dyeing is indebted for its origin, as early in the practice of it precedes the origin of history. From Egypt, the writings of Moses, who led the Israelites out of Egypt about 1553 years before the commencement of the Christian era, it is obvious that the art of dyeing had in his time made great progress in Egypt. He mentions blue, and purple, and scarlet, and badgers' skins dyed red. There are some reasons for believing that what is translated in the Old Testament fine linen was in reality a cloth made of cotton wool. Indeed it is certain that cloth made of cotton was used in India and Egypt in the most remote ages. Cotton wool would naturally attract the attention of mankind in those countries where the plant which yields it grows. Now we know that the cotton plant is a native of India. India and Egypt are countries in which the processes of dyeing are as likely to have originated as any other; for they constitute the cradle of the human race, and civilization appears to have made earlier progress in them than in any other.
The art of dyeing was brought to a considerable degree Tyrian of perfection at a very early period in Phoenicia. It appears dye that it was in Tyre where the method of dyeing woollen cloth purple was first discovered; and this discovery, there is reason to believe, is at least as old as the time of Moses. The purple was communicated by means of several species of univalve shell-fish, which no doubt abounded on the coast of Phoenicia. Pliny, in the thirty-sixth chapter of his sixth book, gives us an account of two species of shell-fish from which the purple was obtained. The first species was called buccinum, doubtless from some resemblance to a hunting horn; the second was called purpura. A single drop of the dyeing liquor was obtained from each fish by opening a vessel situated in the throat of the animal. The liquor, when extracted, was mixed with a considerable portion of salt, to prevent putrefaction. It was then diluted with five or six times as much water, and kept moderately hot in leaden or tin vessels, for the space of ten days, during which the liquor was frequently skimmed, to separate all impurities. After this, the wool, being first washed, was immersed and kept in the liquor for five hours. It was then taken out, carded, and again immersed and kept in the liquor till all the colouring matter was extracted. To produce particular shades of colour, carbonate of soda, urine, and a marine plant called fucus, were occasionally added. Several of these colours are particularly described by Pliny, though it is difficult to form an accurate conception of his meaning. The purple itself seems to have been similar to the colour of blood.
Pliny says the Tyrians first dyed their wool in the liquor of the purpura, and afterwards in that of the buccinum. We find allusions to this practice in several passages of the Old Testament. Doubtless Horace alludes to the same process when he says,
........... te bis Afro Murice tinctae Vestimenta lancea. Of. ii. 16, line 35.
Exodus, xxv. 4 and 5. The shell-fish employed in this process were found abundantly both on the European and African shores of the Mediterranean. They still exist on these shores, and have been also met with abundantly on the coasts of England and France.
The purple mentioned in Exodus was probably that dyed by the Tyrians. Ezekiel, who wrote about 593 years before the Christian era, in his prophecy against Tyre, says, "Fine linen with brodered work from Egypt, was that which thou spreadest forth to be thy sail; blue and purple from the isles of Elishah, was that which covered thee." By Elishah it is generally supposed that Elis, on the west side of the Greek Peloponnesus, was meant. Hence it would appear that the Tyrians in Ezekiel's time drew their supply of shell-fish for dyeing purple from the coast of Greece.
From Herodotus it appears that purple was worn in Greece 559 years before the Christian era. It gradually made its way to Rome, and was purchased with avidity, notwithstanding its high price. After the establishment of the emperors upon the ruins of Roman liberty, the use of the purple was limited to the emperor, people of inferior rank being prohibited from wearing it, on pain of death. This of course sadly diminished the extent of the manufactory. It continued to languish for some centuries, and then became extinct; and the mode of dyeing the Tyrian purple was lost for many ages, but was again revived during the seventeenth century by Mr Cole of Bristol, and during the eighteenth century by M. Reaumur of France. But by this time finer colours had been discovered, and cheaper processes brought into use. It was not therefore thought advisable by the dyers to resume the methods followed by their Tyrian predecessors.
With the exception of the processes followed in the dyeing of purple, we are ignorant of the practices of the ancient dyers, or of the degree of progress which this art had made. Pliny, under whose province an account of dyeing naturally came, has passed it over in silence, and has assigned as a reason for his conduct that it was not reckoned among the liberal arts. Nec lingendi rationem omisit seminum, si quaeram ea liberalium artium fuisse.
The fine colours given in India to cotton cloths are universally known. The methods practised are no modern inventions, but were in common use when India was visited by Alexander the Great, and probably many ages before. These colours, which are both beautiful and permanent, prove that the methods of fixing gaudy colours on cotton were pretty far advanced. But these methods, as they have been described by Beaulieu and Bancroft, are so complicated, tedious, and imperfect, that they could be followed only where the wages of labour are exceedingly low, and never would answer in any part of Europe. There is reason to believe that the processes of dyeing cotton and linen were introduced into Greece only after the expedition of Alexander the Great into India.
The common people in Athens were very idle and very poor, spending their time in the public places, and receiving a daily pension of three oboli, or about fourpence halfpenny. But this sum would have purchased as much corn as three times the amount would do in this country; so that the income of a common Athenian citizen was equivalent to about thirteen pence halfpenny of our money. They went barefooted, and were dressed in garments which never had been dyed, but which were occasionally washed. The rich citizens wore garments which had been dyed; and the most common colour was scarlet, communicated to the cloth by kermes, a dyestuff still in use, and which we shall describe in a subsequent part of this treatise. This colour, as Pliny informs us, was scarcely less esteemed than the Tyrian purple. Cloths of the scarlet colour were worn by the emperors; and scarlet and purple seem to have been often confounded together.
The modes of dyeing black, blue, yellow, and green, were brought by Alexander the Great into Greece from India, as Pliny informs us.
Among the Romans, new-married women wore a yellow veil, and this colour was reserved for the women. In the circus the four different factions were distinguished by four different colours, one belonging to each faction. These were the green (prasimus), the orange (rufustus), the blue (venetus), and the white. These factions, with their colours, were transferred to Constantinople, and long distracted that city. We are ignorant of the dyestuffs by means of which these colours were given to cloth.
The want of soap, which was unknown to the Greeks, and only known to the Romans in Pliny's time as a pomatum for the hair, must have greatly cramped the processes of the ancient dyers; nor have we any evidence that alum was known to them, though they must have employed some substitute, otherwise the red colour of the kermes could not have been fixed upon the cloth. Alum appears to have been well known to Geber, who wrote in the eighth century. He mentions different manufactories of it, and talks of it as a substance familiarly known in his time. Is it not possible that the mode of making it had been known to the Tyrian dyers, but kept by them as a profound secret? The purple and scarlet dye was still in use during Geber's time, and even continued to be practised in the eleventh century. Alum, then, was certainly used by the Tyrian dyers before their manufactory was finally extinguished; but even if we admit that the ancients were unacquainted with alum, yet it is obvious, from Pliny's account of alumen, that it was a substance found native; that there were different species of it, he enumerates four or five, and one of these may have been a native combination of sulphuric acid and alumina, which (if pure) would doubtless answer all the purposes of a mordant.
The ancient dyeing processes, such as they were, continued to be practised in Constantinople as long as the Greek empire lasted. It was during the crusades that the republics of Venice and Genoa reached the highest summit of their power. They were trading and manufacturing communities, and made a point of making themselves acquainted with the different arts at that time practised in Greece. Dyeing was not neglected by them; but the art and trade of the dyers of Constantinople were transferred by them to Italy.
About the year 1300 a merchant of Florence accidentally discovered the method of making archil. He observed that a certain species of lichen (lithos rocellus), when macerated in urine, acquired a fine purple colour. This led him to try various experiments, which terminated in the discovery of archil, and in the application of it to the art of dyeing.
In the year 1429 the first collection of processes employed in dyeing was published in Venice, under the title of Mariagola dell' arte dei Tentori. A second edition of this book, with many additions, was published in 1510. Giovan Ventura Rosetti formed the project of making this
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1 Ezekiel, chap. xxvii. ver. 7. 2 Berthollet has given a catalogue of the dyestuffs of the ancients, after Bischoff, Elements de l'Art de la Teinture, L. 14. We do not consider it as worth transcribing, because it is altogether conjectural. work more complete and more useful. He travelled into those parts of Italy and the neighbouring countries where attention was paid to the processes of dyeing, in order to acquire the requisite information. The result of his acquisitions was published under the name of *Pletho dell arte de tentori, che insegnano tenger panni, tele bambesi e seda, si per l'arte maggiore, come per la commune*. It was published at Venice in the year 1548. A French translation of it appeared in Paris in the year 1716. This book constituted the first attempt at a methodical arrangement of the different processes. It even aimed at something like theory, though the state of knowledge at the time when it was written did not permit any successful explanation of the theory of dyeing.
In the Pletho no notice is taken either of cochineal or indigo. Hence we may conclude that, in 1548, neither of these important dyestuffs had made their way into Europe. Pliny mentions indigo under the name of *indicum*; but it appears to have been used by the Greeks and Romans only as a paint; yet there can be little doubt that in India it had been employed from time immemorial as a dyestuff. Cochineal could not be known till after the discovery of America. It was used by the Mexicans as a dyestuff. In 1523 Cortes received orders from the court of Spain to multiply this precious insect, to collect it, and send it to Spain.
Cochineal by itself gives only a crimson colour; it dyes scarlet when mixed with a solution of tin. This fact was discovered accidentally by Cornelius Drebbel about the year 1630. He communicated his observation to his son-in-law Kuffelar, who was a dyer at Leyden. He soon brought the process to perfection, kept it a secret, and brought the scarlet colour into fashion. Soon after, the same process was discovered by a German chemist called Keffer, who carried his secret to London in 1648. A Flemish dyer called John Kloeeck got information of the process in 1647, and it gradually made its way through every country of Europe.
Indigo, though a much more important dyestuff than cochineal, did not make its way into general use without the greatest difficulty. The use of it was prohibited in England during the reign of Elizabeth; and the prohibition was not taken off till the time of Charles II. It was equally prohibited in Saxony, where it was styled in the prohibition a corrosive substance, and called food for the devil. Restrictions on the use of indigo in dyeing were imposed also in France, though it was not altogether prohibited, as it had been in England and Saxony.
The reason of these prohibitions and restrictions was, that pastel and saoud were employed for dyeing blue; and fears were entertained that indigo would supersede these dyestuffs altogether. Now, as they were the product of the different kingdoms of Europe when they were employed, it was erroneously concluded that the introduction of a better and cheaper dye would injure the country by throwing these plants out of cultivation.
The improvements in dyeing which took place in France may be dated from the administration of Colbert, who paid particular attention to the different branches of manufacture which were carried on by the French. In the year 1672 he caused a book of instructions for dyers to be published in Paris. This book was republished in 1708 under the following title: *Le teinturier parfait, ou instruction nouvelle et générale pour la teinture des laines et manufactures de laine de toutes couleurs, et pour la culture des drogues ou ingredients qu'on y emploie*.
But Colbert's encouragement of dyeing was clogged with restrictions and prohibitions, which would have been fatal to the art, had it not been for the facility with which they were evaded. The revocation of the edict of Nantes in the year 1685 was a fatal blow to the pre-eminence of substances France in manufactures. The most industrious and skilful workmen and artists were driven out of the country, and carried their knowledge and dexterity into Great Britain, Holland, and Prussia. Succeeding administrations endeavoured as far as possible to correct the fatal policy of Louis XIV. The art of dyeing in particular drew their attention, and the most eminent chemists which the country possessed were placed as a kind of superintendents of the art of dyeing. Their business was to endeavour to improve the processes, and to bring the art to a state of perfection. Dufay, Hellot, Macquer, and Berthollet, successively filled this important office; and each of these eminent men contributed somewhat to the improvement of the theory of dyeing. Dufay first formed tolerably accurate notions of the nature of colouring matters, and of the forces which made them attach themselves to cloth. Hellot published a well-arranged treatise on dyeing woollen cloth, such as it was practised in the best dyeing establishments in France; and Macquer gave an equally detailed account of the processes followed by the silk dyers. Macquer indeed meditated a general treatise on dyeing, and published a prospectus in the year 1791. But his great age, and the feeble state of his health for some years before his death, prevented him from completing the undertaking.
Berthollet, who was named his successor as superintendent of dyeing, published an excellent treatise under the title of *Elements de l'Art de la Teinture*, a second edition of which appeared in the year 1804. This work contains a very full and complete account of the processes of dyeing, such as they existed when Berthollet wrote; and is still well entitled to the attention of the practical dyer.
Scarcely any work upon dyeing deserving the name of a scientific treatise appeared in the English language till Bancroft published his *Experimental Researches concerning the Philosophy of Permanent Colours, and the best means of producing them by dyeing, calico printing, &c.* in the year 1794. Of this work a second volume afterwards appeared, not inferior in value to the first. But unfortunately the projected plan was never completed. Had this been the case, the work of Bancroft would have been by far the completest treatise on dyeing in any language.
Great improvements have been made of late years in calico printing, and several new dyeing materials have been introduced. Of these the most important is the dichromate of potash and the sulphate of manganese. The former communicates an indelible yellow, orange, and red; the latter various shades of brown equally indelible, and at present constituting a very fashionable mode of printing. The improvements in the dyeing of silk and woollen cloth are not so easily pointed out, though they are both numerous and important. One, however, may be mentioned: the substitution of the lac dye in most ordinary cases for cochineal. This last dyestuff is still used for giving a scarlet colour to superfine cloth; but for the coarser fabrics lac is almost universally substituted. The calico printers employ only cochineal, and, so far as we know, never use lac.
CHAPTER II.
OF THE NATURE AND PROPERTIES OF THE SUBSTANCES TO WHICH COLOURS ARE COMMUNICATED IN THE PROCESSES OF DYEING.
There has been much speculation among philosophical dyers respecting the nature of the colouring matters, and the way in which the different colours are induced by dye- Substances in; but these speculations have not led to any information of much value. It has been demonstrated by Newton that light is divisible into seven rays, distinguished by the following colours: red, orange, yellow, green, blue, indigo, violet. The colour of an object is owing to its having the property of reflecting or transmitting certain rays, while it absorbs the rest. Thus a red body reflects or transmits the red ray and absorbs the rest, an orange body reflects or transmits red and yellow, a green body reflects or transmits the yellow and blue rays, and a white body all the rays. There is reason for believing that the colouring matters employed as dyestuffs are all transparent, and that the colour is produced by their action on the light transmitted through them from the white fibres of the cloth. Those colouring matters that transmit all the rays equally leave the cloth white; if the blue ray be transmitted and the rest absorbed, the colour of the cloth will be blue, and so on. This is all that we know about the mechanical nature of the dyestuffs. On what the circumstance depends that causes a transparent body to absorb one kind of ray, and transmit another through it, we do not know, nor is it likely that any knowledge will ever be acquired respecting it. The speculations of Delaval, accounting for the colours given by dyestuffs by the size of the colouring particles, appear to us altogether unfounded, and quite inapplicable to the subject under discussion.
With respect to the aptitude of being dyed, and the brilliancy of the colours thus communicated, there is found to be very great difference in different tissues. Animal substances are much more easily dyed than vegetable substances. Of animal substances, silk receives colour, and the shades given are brighter and more beautiful than those which can be imbibed by any other tissue. Woolen cloth is also very fit for being dyed, and receives very brilliant colours with avidity, though in this respect it is inferior to silk. Cotton and linen are much more difficult to dye, and cannot be made to imitate such brilliant colours as silk or woollen. Thus the rich scarlet given to cloth by the combined action of cochineal and the oxide of tin, has never been communicated to cotton cloth or linen. The Turkey-red dye, which is by far the finest and most permanent red that has ever been communicated to cotton cloth, is a crimson, or rather a crimson with a shade of brown. It has not the least approach to a scarlet.
Upon what this difference between animal and vegetable bodies in the capacity of receiving colours depends, we do not know. Both woollen and silk contain a notable quantity of azote among their constituents, while this principle is altogether wanting in cotton and linen. How far the property of easy dyeing depends upon the presence of azote it is impossible to say; but it is the only chemical difference in their constitution that can in the present state of our knowledge be pointed out. Both cotton and flax, so far as their chemical characters have been examined, are precisely similar in their properties to lignin or the woody fibres of trees, supposing them deprived of all their foreign ingredients. Now the constituents of lignin are as follows, according to the analysis of Prout:
| Substance | Quantity | |-----------|----------| | Carbon | 50-00 | | Hydrogen | 5-55 | | Oxygen | 44-45 |
This is proportional to
| Atoms | Quantity | |-------|----------| | Carbon | 3 | | Hydrogen | 2 | | Oxygen | 2 |
Hence these substances (cotton and flax) must either be composed of three atoms carbon, two atoms hydrogen, and two atoms oxygen, or of some multiple of these numbers. How many atoms go to the formation of an intergrate particle of cotton or flax cannot be known till some substance be discovered with which they are capable of entering into infinite combinations.
The only attempt to determine the atomic constituents of silk and wool is that of Dr Ure, according to whom their composition is as follows:
| Substance | Silk | Wool | |-----------|------|------| | Azote | 11-33 | 12-3 | | Carbon | 50-69 | 53-7 | | Hydrogen | 3-94 | 2-8 | | Oxygen | 34-04 | 31-2 |
These are equivalent to the following atomic numbers.
| Substance | Silk | Wool | |-----------|------|------| | Azote | 13 atoms | 14 atoms | | Carbon | 135 | 143 | | Hydrogen | 63 | 45 | | Oxygen | 68 | 62 |
But a comparison between these two sets of bodies will be made with more advantage if we represent the number of atoms of the other constituents of each upon the supposition that the atoms of carbon in each is the same, or 66. On this supposition the composition will stand as follows:
| Substance | Lignin | Silk | Wool | |-----------|--------|------|------| | Azote | 0 atoms | 6-3 atoms | 6-5 atoms | | Carbon | 66-0 | 66-0 | 66-0 | | Hydrogen | 30-8 | 20-7 | 20-7 | | Oxygen | 33-2 | 28-5 | 28-5 |
If the analyses of these bodies constituted a near approximation to the truth, it would follow from a comparison of them: 1. That in lignin the hydrogen and oxygen exist in the proportions which constitute water, while in silk there exists an excess of oxygen, and in wool this excess is still greater. 2. In lignin there is no azote, whereas in silk and wool the atoms of azote amount to about one tenth of the atoms of carbon. 3. The atoms of hydrogen in silk are to those in lignin as three to four, and in wool as two to four; so that lignin contains twice as much hydrogen as wool does. 4. In silk the atoms of oxygen are to those in lignin very nearly as three to four; but in wool the number of atoms of oxygen is to that in lignin rather in a less ratio than that of three to four.
These facts lead us but a very little way in discovering the difference between the nature of silk and wool, and that of cotton and flax; but they contain all the information which chemistry at present is able to furnish. We shall now state, in the following sections, the differences which have been observed in the mechanical structure of these different substances.
**Sect. I.—Of Wool.**
Wool, which is well known as the covering of sheep, derives its value from the length and fineness of its filaments. The filaments of wool are considerably elastic, for they may be drawn out beyond their usual length, and when the force is removed, they recover it again. The surface of the filaments of wool or hair is not perfectly smooth; for although no roughness or inequality can be discovered by the microscope, yet they seem to be formed of small laminae placed over each other in a slanting direction, from the root of the filament towards its point, resembling the arrangement of the scales of a fish, which cover each other from the head of the animal to its tail; or perhaps they consist of zones placed over each other, This peculiarity of structure of the filaments of hair and wool is proved by a simple experiment. If a hair be laid hold of by the root in one hand, and drawn between the fingers of the other hand, from the root towards the point, scarcely any friction or resistance is perceived, and no noise is heard; but if it be grasped by the point, and passed in the same manner between the fingers from the point towards the root, a resistance is felt, and a tremulous motion is perceptible to the touch, while the ear is sensible to a slight noise. Thus it appears, that the texture of the surface of hair or wool is not the same from the root towards the point, as it is from the point towards the root. This is further confirmed by another experiment. If a hair be held between the thumb and fore finger, and they are rubbed against each other in the longitudinal direction of the hair, it acquires a progressive motion towards the root. This effect depends not on the nature of the skin of the finger, or on its texture, for if the hair be turned, and the point placed where the root formerly was, the motion is reversed, that is, it will still be towards the root.
On this peculiarity of structure, which was observed by M. Monge, depend the processes of felting and fulling, to which hair and wool are subjected for different purposes. In the process of felting, the flocculi of wool are struck with the string of the bow, by which the filaments are separately detached, and dispersed in the air. These filaments fall back on each other in all directions on the table, and when a layer of a certain thickness is formed, they are covered with a cloth, on which the workman presses with his hands in all parts. By this pressure the filaments of wool are brought nearer to each other; the points of contact are multiplied; the progressive motion towards the root is produced by the agitation; the filaments entangle each other; and the laminae of each filament taking hold of those of the other filaments, which are in an opposite direction, the whole is retained in the state of close contexture.
Connected with this operation is that of fulling. The roughness on the surface of the filaments of wool, and their tendency to acquire a progressive motion towards the root, produce considerable inconvenience in the operations of spinning and weaving. These inconveniences are obviated by covering the filaments with a coat of oil, which fills up the cavities, and renders the asperities less sensible. When these operations are finished, the stuff must be freed from the oil, which would prevent it from taking the colour with which it is to be dyed. For this purpose it is taken to the fulling-mill, where it is beaten with large beetles, in a trough of water, through which clay has been diffused. The clay unites with the oil, which being thus rendered soluble in the water, is carried off by fresh portions of water, conveyed to it by proper apparatus. In this way the stuff is scoured; but this is not the sole object of the operation. By the alternate pressure of the beetles, an effect similar to that of the hands in the operation of felting is produced. The filaments composing a thread of warp or woof, acquire a progressive motion, are entangled with the filaments of the adjoining threads, those of the latter into the next, and so on, till the whole threads are felted together. The stuff is now contracted in all its dimensions, and, participating both of the nature of cloth and of felt, may be cut without being subjected to ravel; and, when employed to make a garment, requires no hemming. In a common woollen stocking web, after this operation, the stitches, when one happens to slip, are now no longer subject to run, and the substances of the warp and woof being less distinct from each other, the whole stuff is thickened, and forms a warmer clothing.
The various manufactures of which wool constitutes the basis are justly regarded as among the most important toance of man in civilized society. Accordingly, the production of fine wool, and the causes which retard or improve the breed of sheep from which it is obtained, have greatly occupied the attention of economists and philosophers in our own, as well as in other countries. The wool of different breeds of sheep, in different countries, it is well known, possesses very different qualities, both with regard to the fineness of the filament, and the colour. Some is of a white or yellow, and some of a reddish and black colour. Excepting the wool of the breed of sheep in Andalusia, the Spanish wool was formerly all of a brownish-black colour. This was preferred by the native Spaniards; and even at this day, the dress of some religious orders in Roman Catholic countries consists of cloth manufactured from this wool, and retaining its natural colour. But for the purposes of dyeing, white wool is now always preferred, because it is found susceptible of receiving better and more durable colours.
Wool is naturally covered with a kind of grease or oil, Scouring which is found to preserve it from insects or moths, and on this account this greasy matter is not removed, or the wool is not scoured, till it is to be dyed or spun. The process for scouring wool is the following: It is put for about a quarter of an hour into a kettle, with a sufficient quantity of water, to which a fourth part of putrid urine has been added. It is then heated to such a degree as the hand can bear, occasionally stirred, and, after being taken out, is allowed to drain. It is then put into a basket, and exposed to a stream of running water, and moved until the grease is so completely separated that it no longer renders the water turbid. After being drained, it is sometimes found to lose by this operation above one fifth of its weight. It is almost unnecessary to observe, that the more carefully and completely this process is performed, the better the wool is fitted to receive the colouring matter. Our chemical readers will readily perceive the nature of the changes which are effected in this process of scouring. The ammonia, or volatile alkali, which exists in the urine, combines with the oil of the wool, and forms a soap, which being soluble in water, is dissolved and carried off.
Wool is either dyed in the fleece, or after it is spun Dyeing into threads, or when it has been manufactured into cloth. For the purpose of forming cloths of mixed colours, it is dyed before it is spun; for the purposes of tapestry, it is dyed in the state of thread; but most commonly it is subjected to this process after it has been manufactured into cloth. In these different states the quantity of colouring matter which is taken up is very different. The proportion is largest when it is dyed in the fleece, because then the filaments being more separated, a greater surface is exposed to the action of the colouring particles. For a similar reason the quantity of colouring matter taken up is greater when in the state of thread or yarn, than when it is formed into cloth. But cloths themselves must vary greatly in this respect, according to their different qualities. Their different degrees of fineness, or closeness of texture, will produce considerable variations; and besides, the difference in the quantity and dimensions of the substances to be dyed, the different qualities of the ingredients employed in the process, and the different circum-
According to an observation of Reaumur, rubbing any stuff with greasy wool is sufficient to preserve it from moths. Substances in which it is performed, should be a caution against trusting to precise quantities, regulated by weight or measure, which are recommended according to general rules. According to the fineness of the texture of the wool, and the nature of the colouring matter employed, it is found to be more or less penetrated with this matter. The coarse wool from the thighs and tails of some sheep receives colours with difficulty, and the finest cloth is never completely penetrated with the scarlet dye. The interior of the cloth appears always, when cut, of a lighter shade, and sometimes even white.
Sect. II.—Of Silk.
Silk, which forms the basis of one of the richest and most splendid parts of dress among the wealthy and luxurious in civilized society, is the production of different species of insects. The *phalerae bombix*, or silk-worm, which is a native of China, attracted the attention of mankind in that country from the earliest ages. The honour of having first collected and prepared silk from the cocoons or balls in which it is wound up by the insect, during its metamorphosis, is ascribed by the Chinese historians to the wife of an emperor. The *phalerae atlas*, Lin., which is also a native of China, is said to form larger cocoons, and to yield a stronger silk. The silk-worm was first carried from China to Hindustan, and afterwards to Persia. Silk seems not to have been known to the Greeks or Romans till the time of Augustus. Its nature and origin were little understood; and for many ages it was so scarce that it could only be purchased at a price which was equal to its weight in gold. The emperor Aurelian, it is said, from a principle of economy, resisted the urgent solicitations of his empress, who wished to have a silken robe, alleging the extravagance of the expense. About the middle of the sixth century, two monks returned from India to Constantinople, and brought with them a considerable number of silk-worms, with instructions for managing and breeding them, as well as for collecting, preparing, and manufacturing the silk. Establishments were thus formed at Corinth, Athens, and other parts of Greece. The crusades, which greatly contributed to the diffusion of different kinds of knowledge, by the intercourse which took place between different countries, proved useful in disseminating the knowledge of rearing the silk-worm, and preparing and manufacturing its valuable productions. Roger, king of Sicily, about the year 1130, returning from one of these frantic expeditions, brought with him from Athens and Corinth several prisoners, who were acquainted with the management of silk-worms and the manufacturing of silk. Under their superintendence manufactories were established at Palermo and Cagliari in Sicily. This example was soon adopted and followed in different parts of Italy and Spain. In the time of James I, an attempt was made to establish the silk-worm in England. For this purpose the culture of the mulberry-tree, on which the insects feed, was strongly recommended by that prince to his subjects; but the attempts which were made have been hitherto unsuccessful.
The fibres of silk are covered with a coating or natural varnish of a gummy nature. To this is ascribed its stiffness and elasticity. Besides this varnish, the silk which is usually met with in Europe is impregnated with a substance of a yellow colour; and for most of the purposes to which silk is applied, it is necessary that it should be deprived both of the varnish and of the colouring matter. On this account it must be subjected to the operation of scouring; but for silks which are to be dyed this process should not be carried so far as for those which are merely to be whitened; and different colours, it is observed, require different degrees of this operation. The quantity of soap constitutes the chief difference. A hundred pounds of silk boiled in a solution of twenty pounds of soap for three or four hours, adding new portions of water during the evaporation, are sufficiently prepared for receiving common colours. For blue colours, the proportion of soap must be increased; and scarlet, cherry colour, &c. require a still greater proportion, for the ground must be whiter for these colours.
Silk which is to be employed white must undergo three operations. In the first the banks are immersed in a hot but not boiling solution of thirty pounds of soap to a hundred of silk. When the immersed part is freed from its gum, which is known by its whiteness, the banks are shaken over, as the workmen term it, so that the part which was not previously immersed may undergo the same operation. They are then wrung out as the operation is completed. In the second operation the silk is put into bags of coarse cloth; each bag containing twenty or thirty pounds. These bags are boiled for an hour and a half in a solution of soap prepared as before, but with a smaller proportion of soap; and, that they may not receive too much heat by touching the bottom of the kettle, they must be constantly stirred during the operation. The object of the third operation is to communicate to the silk different shades, to render the white more agreeable. These are known by different names, as China-white, silver-white, azure-white, or thread-white. For this purpose a solution of soap is also prepared, of which the proper degree of strength is ascertained by its manner of frothing by agitation. For the China-white, which is required to have a slight tinge of red, a small quantity of anotta is added, and the silk is shaken over in it till it has acquired the shade which is wanted. In other whites a blue tinge is given by adding a little blue to the solution of soap. The azure-white is communicated by means of indigo. To prepare the azure, fine indigo is well washed two or three times in moderately warm water, ground fine in a mortar, and boiling water poured upon it. It is then left to settle, and the liquid part only, which contains the finer and more soluble parts, is employed.
Some use no soap in the third operation; but when the second is completed, they wash the silks, fumigate with sulphur, and azure them with river water, which should be very pure. But all these operations are not sufficient to give silk that degree of brightness which is necessary, when it is to be employed in the manufacture of white stuffs. For this purpose it must undergo the process of sulphuration, in which the silk is exposed to the vapour of sulphur; for an account of which see BLEACHING. But before the silk which has been treated in this way is fit for receiving colours, and retaining them in their full lustre, the sulphur which adheres to it must be separated by immersion and agitation for some time in warm water, otherwise the colours are tarnished and greatly injured.
It has long been an object of considerable importance to deprive silk of its colouring matter, without destroying the gum, on which its stiffness and elasticity depend. A new process for this purpose was discovered by Beaumé, but as it was not made public, others have been led to it by conjecture and experiment. The following account, given by Berthollet, is all that has transpired concerning this process. A mixture is made with a small quantity of muriatic acid and alcohol. The muriatic acid should be in a state of purity, and particularly should be entirely free from nitric acid, which would give the silk a yellow colour. In the mixture, thus prepared, the silk is to be immersed.
One of the most difficult parts of the process, espe-