the art of whitening linen cloth, thread, bleaching thread, &c., which is conducted in the following manner by the bleachers of this country.

After the cloth has been sorted into parcels of an equal fineness, as near as can be judged, they are latched, linked, and then steeped. Steeping is the first operation which the cloth undergoes, and is performed in this manner. The linens are folded up, each piece distinct, and laid in a large wooden vessel; into which is thrown, blood-warm, a sufficient quantity of water, or equal parts of water and lye, which has been used to white cloth only, or water with rye-meal or bran mixed with it, till the whole is thoroughly wet, and the liquor rises over all. Then a cover of wood is laid over the cloth, and that cover is secured with a post betwixt the boards and the joistling, to prevent the cloth from rising during the fermentation which ensues. About six hours after the cloth has been steeped in warm water, and about twelve in cold, bubbles of air arise, a pellicle is formed on the surface of the liquor, and the cloth swells when it is not pressed down. This intestine motion continues from 36 to 48 hours, according to the warmth of the weather; about which time the pellicle or scum begins to fall to the bottom. Before this precipitation happens, the cloth must be taken out; and the proper time for taking it out, is when no more air-bubbles arise. This is allowed to be the safest guide by the most experienced bleachers.

The cloth is then taken out, well rinsed, disposed regularly by the felvage, and washed in the pot-mill to carry off the loofe dust. After this it is spread on the field to dry. When thoroughly dried, it is ready for bucking; which is the second operation.

Bucking, or the application of salts, is performed in this manner. The first, or mother lye, is made in a copper, which we shall suppose, for example, when full, holds 170 Scots gallons of water. The copper is filled three-fourths full of water, which is brought to boil: just when it begins, the following proportion of ashes is put into it, viz. 30 lb. of blue, and as much white pearl ashes; 200 lb. of Marcott ashes (or, if they have not these, about 300 lb. of Calshub); 300 lb. of Mucovoy, or blanch ashes; the three last ought to be well pounded. This liquor is allowed to boil for a quarter of an hour, stirring the ashes from the bottom very often; after which the fire is taken away. The liquor must stand till it has settled, which takes at least six hours, and then it is fit for use.

Out of their first, or mother-lye, the second, or that used in bucking, is made in this manner. Into another copper, holding, for example, 40 Scots gallons, are put 38 gallons of water, 2 lb. soft soap, and 2 gallons of mother-lye; or, for cheapness, in place of the soap, when they have lye which has been used to white linen, called white linen lye, they take 14 gallons of it, leaving out an equal quantity of water. This is called bucking-lye.

After the linens are taken up from the field dry, they are set in the vat or cove, as their large vessel is called, in rows, endwise, that they may be equally wet by the lye; which, made blood-warm, is now thrown on them, and the cloth is afterwards squeezed down by a man with wooden shoes. Each row undergoes the same operation, until the vessel is full, or all the cloth in it. At first the lye is put on milk-warm, and, after standing a little time on the cloth, it is again let off by a cock into the bucking-copper, heated to a greater degree, bleaching, and then put on the cloth again. This course is repeated for five or seven hours, and the degree of heat gradually increased, till it is, at the last turn or two, thrown on boiling hot. The cloth remains after this for three or four hours in the lye; after which the lye is let off, thrown away, or used in the first buckings, and the cloth goes on to another operation.

It is then carried out, generally early in the morning, spread on the grass, pinned, corded down, exposed to the sun and air, and watered for the first six hours, so often, that it never is allowed to dry. Afterwards it is allowed to lie till dry spots appear before it is watered. After seven at night it gets no more water, unless it be a very drying night. Next day, in the morning and forenoon, it is watered twice or thrice if the day be very dry; but if the weather be not drying, it gets no water. After which it is taken up dry if the green be clean; if not, it is rinsed, mill-washed, and laid out to dry again, to become fit for bucking.

This alternate course of bucking and watering is performed for the most part from ten to sixteen times, or more, before the linen is fit for souring; gradually increasing the strength of the lye from the first to the middle buckings, and from that gradually decreasing it till the souring begins. The lyes in the middle buckings are generally about a third stronger than the first and last.

Souring, or the application of acids to cloth, is the fourth operation. It is difficult to say when this operation should commence, and depends mostly on the skill and experience of the bleacher. When the cloth has an equal colour, and is mostly freed from the sprat, or outer bark of the lint, it is then thought fit for souring; which is performed in the following manner. Into a large vat or vessel is poured such a quantity of buttermilk, or four milk, as will sufficiently wet the first row of cloth; which is tied up in loofe folds, and pressed down by two or three men bare-footed. If the milk is thick, about an eighth of water is added to it; if thin, no water. Sours made with bran, or rye-meal and water, are often used instead of milk, and used milk-warm. Over the first row of cloth a quantity of milk and water is thrown, to be imbibed by the second; and so it is continued till the linen to be soured is sufficiently wet, and the liquor rises over the whole. The cloth is then kept down by covers filled with holes, and secured with a post fixed to the joist, that it may not rise. Some hours after the cloth has been in the four, air-bubbles arise, a white scum is found on the surface, and an intestine motion goes on in the liquor. In warm weather it appears sooner, is stronger, and ends sooner, than in cold weather. Just before this fermentation, which lasts five or six days, is finished, at which time the scum falls down, the cloth should be taken out, rinsed, mill-washed, and delivered to the women to be washed with soap and water.

Washing with soap and water is the fifth operation; and is performed thus. Two women are placed opposite at each tub, which is made of very thick flaves, so that the edges, which slope inwards, are about four inches in thickness. A small vessel full of warm water is placed in each tub. The cloth is folded so that the felvage may be first rubbed with soap and warm water lengthwise, till it is sufficiently impregnated with it. Bleaching. In this manner all the parcel is rubbed with soap, and afterwards carried to be bucked.

The lye now used has no soap in it, except what it gets from the cloth; and is equal in strength to the strongest formerly used, or rather stronger, because the cloth is now put in wet. From the former operation these lyes are gradually made stronger, till the cloth seems of an uniform white, nor any darkness or brown colour appears in its ground. After this the lye is more speedily weakened than it was increased; so that the last which the cloth gets is weaker than any it got before.

But the management of fours is different; for they are used strongest at first, and decreased so in strength, that the last four, considering the cloth is then always taken up wet, may be reckoned to contain three-fourths of water.

From the bucking it goes to the watering, as formerly, observing only to overlap the selvages, and tie it down with cords, that it may not tear; then it returns to the four, milling, washing, bucking, and watering again. These operations succeed one another alternately till the cloth is whitened; at which time it is blued, starched, and dried.

This is the method used in the whitening fine cloths. The following is the method used in the whitening of coarse cloths.

Having sorted the cloths according to their quality, they are steeped in the same manner as the fine, rinsed, washed in the mill, and dried before boiling.

In this process boiling supplies the place of bucking, as it takes less time, and consequently is thought cheaper. It is done in the following manner: 200 lb. caulked-ashes, 100 lb. white Mutovy, and 30 lb. pearl-ashes, boiled in 105 Scots gallons of water for a quarter of an hour, as in the process for the fine cloth, makes the mother or first lye. The cloth-boiler is then to be filled two-thirds full with water and mother-lye, about nine parts of the former to one of the latter; so that the lye used for boiling the coarse cloth is about a third weaker than that used in bucking the fine. Such a quantity of cloth is put into the foregoing quantity of lye, when cold, as can be well covered by it. The lye is brought gradually to the boil, and kept boiling for two hours; the cloth being fixed down all the time, that it does not rise above the liquor. The cloth is then taken out, spread on the field, and watered, as mentioned before in the fine cloth.

As the salts of the lye are not exhausted by this boiling, the same is continued to be used all that day, adding, at each boiling, so much of the mother-lye as will bring it to the same strength as at first. The lye by boiling loses in quantity somewhat between a third and a fourth; and they reckon that in strength it loses about a half, because they find in practice, that adding to it half its former strength in fresh lye, has the same effect on cloth. Therefore some fresh lye, containing a fourth part of the water, and the half of the strength of the first lye, makes the second boiler equal in strength to the first. To the third boiler they add somewhat more than the former proportion, and go on still increasing gradually to the fourth and fifth, which is as much as can be done in a day. The boiler is then cleaned, and next day they begin with fresh lye. These additions of fresh lye ought always to be made by the master-bleacher, as it requires judgment to bring succeeding lyes to the same strength as the first.

When the cloth comes to get the second boiling, the lye should be a little stronger, about a thirtieth part, and the deficiencies made up in the same proportion. For six or seven boilings, or fewer, if the cloth be thin, the lye is increased in this way, and then gradually diminished till the cloth is fit for souring. The white cloth ought always to be boiled first, that it may not be hurt by what goes before.

In this process, if the cloth cannot be got dry for boiling, business does not stop as in the fine; for after the coarse has dreeped on racks made for the purpose, it is boiled, making the lye strong in proportion to the water in the cloth.

The common method of souring coarse linen is, to mix some warm water and bran in the vat, then put a layer of cloth, then more bran, water, and cloth; and so on, till the cave is full. The whole is tramped with men's feet, and fixed as in the former process. A thousand yards of cloth, yard-broad, require between four and six pecks of bran. The cloth generally lies about three nights and two days in the four. Others prepare their four twenty-four hours before, by mixing the bran with warm water in a separate vessel; and before pouring it on the cloth, they dilute it with a sufficient quantity of water. After the cloth is taken from the four, it ought to be well washed and rinsed again. It is then given to men to be well soaked on a table, and afterwards rubbed between the rubbing-boards. When it comes from them, it should be well milled, and warm water poured on it all the time, if convenience will allow of it. Two or three of these rubbings are sufficient, and the cloth very seldom requires more.

The lye, after the souring begins, is decreased in strength by degrees; and three boilings after that are commonly sufficient to finish the cloth. Afterwards it is starched, blued, dried, and bittled in a machine made for that purpose, which supplies the place of a calender, and is preferred by many to it.

This method used in the bleaching of our coarse cloths, is very like that practised in Ireland for both fine and coarse. The only material difference is, that there the bleachers use no other ashes but the kelp or caulk. A lye is drawn from the former by cold water, which dissolves the salts, and not the sulphureous particles of the kelp-ashes. This lye is used till the cloth is half whitened, and then they lay aside the kelp-lye for one made of caulked-ashes.

In the preceding history of bleaching we may observe, that it naturally divides itself into several different branches or parts, all tending to give linen the degree of whiteness required. How they effectuate that comes next to be considered.

The general process of bleaching divides itself into these different parts. 1. Steeping and milling. 2. Bucking and boiling. 3. Alternate watering and drying. 4. Souring. 5. Rubbing with soap and warm water, starching, and bluing. We shall treat of these different parts in their order.

Steeping. Green linen, in the different changes which it has undergone before it arrives at that state, contracts a great foulness. This is chiefly communicated to it by the dressing composed of tallow and soot, which Bleaching is a kind of flummery made of bran, flour, or oat-meal seeds. The first thing to be done in the bleachfield is to take off all that filth which is foreign to the flax, would blunt the future action of the salts, and might, in unskillful hands, be fixed in the cloth. This is the design of steeping.

To accomplish this end, the cloth is laid to steep in blood-warm water. A smaller degree of heat would not dissolve the dressing so soon; and the greater might coagulate and fix, in the body of the linen, those particles which we design to carry off. In a few hours the dressing made use in weaving is dissolved, mixed with the water; and as it had acquired some degree of acidity before application, it becomes a species of ferment. Each ferment promotes its own particular species of fermentation or intestine motion; the putrid ferment sets in motion the putrefactive fermentation; the vinous ferment gives rise to the vinous fermentation; and the acid ferment to the acetous fermentation. That there is a real fermentation going on in steeping, one must be soon convinced, who attends to the air-bubbles which immediately begin to arise, to the scum which gathers on the surface, and to the intestine motion and swelling of the whole liquor. That it must be the acetous fermentation, appears from this, that the vegetable particles, already in part soured, must first undergo this process.

The effect of all fermentations is to set the liquor in motion; to raise in it a degree of heat; and to emit air-bubbles, which, by carrying up some of the light oleaginous particles along with them, produce a scum. But as the dressing is in small quantity in proportion to the water, these effects are gentle and slow. The acid salts are no sooner separated, by the acetous fermentation, from the absorbent earth, which made them not perceptible to the tongue in their former state, than they are united to the oily particles of the tallow, which likewise adhere superficially, dissolve them, and render them in some degree miscible with water. In this state they are soon washed off by the intestine motion of the liquor. The consequence of this operation is, that the cloth comes out freed in a great measure from its superficial dirt, and more pliant and soft than what it was.

Whenever this intestine motion is pretty much abated, and before the scum subsides, bleachers take out their cloth. The scum, when no more air-bubbles rise to support it, separates and falls down; and would again communicate to the cloth great part of the filth. But a longer stay would be attended with a much greater disadvantage. The putrid follows close upon the acetous fermentation: when the latter ends, the former begins. Were this to take place in any considerable degree, it would render the cloth black and tender. Bleachers cannot be too careful in this article.

The first question that arises to be determined on these principles is, What is the properest liquor for steeping cloth? those used by bleachers are plain water; white linen lye and water, equal parts; and rye-meal or bran mixed with water. They always make use of lye when they have it.

After steeping, the cloth is carried to the puttflock-mill, to be freed of all its loose foulness. There can be nothing contrived so effectual to answer the purpose as this mill. Its motion is easy, regular, and safe. While it presses gently, it turns the cloth; which is continuously washed with a stream of water. Care must be taken that no water be detained in the folds of the linen, otherwise that part may be damaged.

Bucking and boiling. This is the most important operation of the whole process, and deserves a thorough examination. Its design is to loosen, and carry off, by the help of alkaline lixives or lyes, that particular substance in cloth, which is the cause of its brown colour.

All ashes used in lye, the pearl excepted, ought to be well pounded, before they are put into the copper; for the Marcott and Cashub are very hard, and with some difficulty yield their salt. As these two last contain a very considerable proportion of a real sulphureous matter, which must in some degree tinge white cloth; and as this is dissolved much more by boiling than by the inferior degrees of heat, while the salts may be as well extracted by the latter; the water should never be brought to boil, and should be continued for some time longer under that degree of heat. The pearl-ashes should never be put in till near the end, as they are easily dissolved in water.

If the salts were always of an equal strength, the same quantities would make a lye equally strong; but they are not. Salts of the same name differ very much from one another. The Mulcoy ashes are turning weaker every day, as every bleacher must have observed, till at last they turn quite effete. A deviation from them when new, must differ very much from one when they have been long kept. Hence a necessity of some exact criterion to discover when lyes are of an equal strength. The taste cannot serve as that is so variable; cannot be described to another, and is blunted by repeated trials. The proof-ball will serve the purpose of the bleachfield sufficiently; and, by discovering the specific gravity, will show the quantity of alkaline salts dissolved. But it cannot show the dangerous qualities of these salts; for the less caustic and less heavy this liquor is, the more dangerous and corrosive it may be for the cloth.

The third lye, which they draw from these materials by an infusion of cold water, in which the taste of lime is discoverable, appears plainly to be more dangerous than the first. The second lye, which they extract from the same ashes, and which is reckoned about a third in strength, when compared to the first, must be of the same nature; nor should it be used without an addition of pearl-ashes, which will correct it.

It is taken for a general rule, That the solution of any body in its menstruum is equally diffused through the whole liquor. The bleachers depending on this, use equal quantities of the top and bottom of their lye, when once clear and settled; taking it for granted, that there is an equal quantity of salts in equal quantities of the lye. But if there is not, the mistake may be of fatal consequence, as the lye may be in some places stronger than what the cloth can with safety bear. That general law of solution must have taken its rise from particular experiments, and not from reasoning. Whether a sufficient number of experiments have been tried to ascertain this point, and to establish an undoubted general rule, may be called in question.

"But (says Dr Home) when I had discovered that lime makes part of the dissolved substance, and reflected how long its grosser parts will continue suspended in water, there appeared stronger reasons for suspecting..." suspecting that this rule, tho' it may be pretty general, does not take place here; at least it is worth the pursuit of experiment.

"I weighed at the bleachfield a piece of glass in some cold lye, after it had been boiled, stood for two days; and about the fourth part of it had been used. The glass weighed 3 drams 1½ grains in the lye, and 3 drams 7½ grains in river-water. The same glass weighed in the same lye, when almost all used, 2 grains less than it had done before. This shows, that the last of the lye contained a third more of the dissolved body; and, consequently, was a third stronger than the first of the lye.

"As this might, perhaps, be owing to a continuation of the solution of the salts, I repeated the experiment in a different way.

"I took from the surface some of the lye, after the salts were dissolved, and the liquor was become clear. At the same time I immersed a bottle, fixed to a long stick, so near the bottom, as not to raise the ashes there, and, by pulling out the cork by a string, filled the bottle full of the lye near the bottom. The glass weighed in river-water 3 drams 38½ grains; in the lye taken from the surface 3 drams 34½ grains; and in the lye taken from the bottom 3 drams 31½ grains. This experiment shows, that the lye at the bottom was, in this case, ¾ this stronger than the lye at the surface.

"At other times when I tried the same experiment, I found no difference in the specific gravity; and therefore, I leave it as a question yet doubtful, though deserving to be ascertained by those who have an opportunity of doing it. As the lye stands continually on the ashes, there can be no doubt but what is used last must be stronger than the first. I would therefore recommend, to general practice, the method used by Mr John Christie, who draws off the lye, after it has settled into a second receptacle, and leaves the ashes behind. By this means it never can turn stronger; and he has it in his power to mix the top and bottom, which cannot be done so long as it stands on the ashes."

Having considered the lye, let us next inquire how it acts. On this inquiry depends almost the whole theory of bleaching, as its action on cloth is, at least in this country, absolutely necessary. It is found by experiment, that one effect they have on cloth is the diminishing of its weight; and that their whitening power is, generally, in proportion to their weakening power. Hence arises a probability, that these lyes act by removing somewhat from the cloth, and that the loss of this substance is the cause of whiteness. This appears yet plainer, when the bucking, which lasts from Saturday night to Monday morning, is attended to.

There are various and different opinions with regard to the operations of these salts: that they act by altering the external texture of the cloth, or by separating the mucilaginous parts from the rind, or by extracting the oil which is laid up in the cells of the plant. The last is the general opinion, or rather conjecture, for none of them deserves any better name; but we may venture to affirm, that it is so without any better title to pre-eminence than what the others have. Alkaline salts dissolve oils, therefore these salts dissolve the cellular oil of the cloth, is all the foundation which this theory has to rest on; too slight, when unsupported by experiment, to be relied on.

Dr Home endeavours to settle this question by the following experiments and observations.

"Wax (lys he) is whitened by being exposed to the influence of the sun, air, and moisture. A discovery of the change made on it by bleaching may throw a light upon the question.

"Six drams of wax were sliced down, exposed on a south window, September 10, and watered. That day being clear and warm, bleached the wax more than all the following. It seemed to me to whiten quicker when it had no water thrown on it than when it had. September 15, it was very white, and 1 dram 3 grains lighter. 3½ drams of this bleached wax, and as much of unbleached, taken from the same piece, were made into two candles of the same length and thickness, having cotton wicks of the same kind. The bleached candle burnt 1 hour 33 minutes; the unbleached 3 minutes longer. The former run down four times, the latter never. The former had an obscure light and dull flame; the latter had a clear pleasant one, of a blue colour at the bottom. The former when burning seemed to have its wick thicker, and its flame nearer the wax, than the latter. The former was brittle, the latter not. It plainly appears from these facts, that the unbleached wax was more inflammable than the bleached; and that the latter had lost so much of an inflammable substance as it had lost in weight; and consequently the substance lost in bleaching of wax is the oily part.

"As I had not an opportunity of repeating the former experiment, I do not look on it as entirely conclusive; for it is possible that some of the dust, flying about in the air, might have mixed with the bleached wax, and to have rendered it less inflammable. Nor do I think the analogical reasoning from wax to linen without objections. Let us try then if we cannot procure the substance extracted from the cloth, show it to the eye, and examine its different properties. The proper place to find it, is in a lye already used, and fully impregnated with these colouring particles.

"I got in the bleachfield some lye, which had been used all that day for boiling coarse linen, which was tolerably white, and had been twice boiled before. There could be no dressing remaining in these webs. No soap had ever touched that parcel; nor do they mix soap with the lye used for coarse cloth. Some of this impregnated lye was evaporated, and left a dark coloured matter behind. This substance felt oily betwixt the fingers, but would not lather in water as soap does. It deliquesced with nitre in fusion, and afforded a tincture to spirit of wine. By this experiment the salts seem to have an oily inflammable substance joined with them.

"Could we separate this colouring substance from these salts, and exhibit it by itself, so that it might become the object of experiment, the question would be soon decided. Here chemistry lends us its assistance. Whatever has a stronger affinity or attraction to the salts with which it is joined than this substance has, must set it at liberty, and make it visible. Acids attract alkaline salt from all other bodies; and therefore will serve our purpose.

"Into "Into a quantity of the impregnated lye mentioned in the former experiment, I poured in oil of vitriol. Some bubbles of oil arose, an intestine motion was to be perceived, and the liquor changed its colour from a dark to a turbid white. It curdled like a solution of soap, and a scum soon gathered on the surface, about half an inch in thickness, the depth of the liquor not being above five inches. What was below was now pretty clear. A great deal of the same matter lay in the bottom; and I observed that the substance on the surface was precipitated, and showed itself heavier than water, when the particles of air, attached to it in great plenty, were dispelled by heat. This substance was in colour darker than the cloth which had been boiled in it.

"I procured a considerable quantity of it by skimming it off. When I tried to mix it with water, it always fell to the bottom. When dried by the air, it diminished very much in its size, and turned as black as a coal. In this state it deflagrated strongly with nitre in fusion; gave a strong tincture to spirit of wine; and when put on a red-hot iron, burnt very slowly, as if it contained a heavy ponderous oil; and left some earth behind.

"From the inflammability of this substance, its rejecting of water, and dissolving in spirit of wine, we discover its oleaginous nature; but from its great specific gravity we see that it differs very much from the expressed or cellular oil of vegetables; and yet more from their mucilage. That it dissolves in spirit of wine, is not a certain argument of its differing from expressed oils; because these, when joined to alkaline salts, and recovered again by acids, become soluble in spirit of wine. The quantity of earthy powder left behind after burning, shows that it contains many of the solid particles of the flax. The substance extracted from cloth by alkaline lyes appears then to be a composition of a heavy oil, and the solid earthy particles of the flax.

"In what manner these salts act so as to dissolve the oils, and detach the solid particles, is uncertain; but we see evidently how much cloth must be weakened by an improper use of them, as we find the solid particles themselves are separated."

It is necessary that cloth should be dry before bucking, that the salts may enter into the body of the cloth along with the water; for they will not enter in such quantity if it be wet; and by acting too powerfully on the external threads, may endanger them.

The degree of heat is a very material circumstance in this operation. As the action of the salts is always in proportion to the heat, it would appear more proper to begin with a boiling heat, by which a great deal of time and labour might be saved. The reason why this method is not followed appears to be this. If any vegetable or vegetable substance is to be softened and to have its juices extracted, it is found more proper to give it gentle degrees of heat at first, and to advance gradually, than to plunge it all at once in boiling water. This last degree of heat is so strong, that when applied at once to a vegetable it hardens instead of softening its texture. Dried vegetables are immediately put into boiling water by cooks, that these substances may preserve their green colour, which is only to be done by hindering them from turning too soft. Boiling water has the same effect on animal substances; for if salt beef is put into it, the water is kept from getting at the salts from the outside of the beef being hardened.

But when we consider how much of an oily substance there is in the cloth, especially at first, which will for some time keep off the water, and how the twisting of the threads, and closeness of the texture, hinders the water from penetrating, we shall find, that if boiling water were put on it at once, the cloth might be liable, in several parts, to a dry heat, which would be much worse than a wet one. That the lyes have not access to all parts of the cloth, at first, appears plainly from this, that when it has lain, after the first bucking, till all the lyes are washed out, it is as black, in some parts, as when it was steeped. This must be owing to the discharge of the colouring particles from those places to which the lye has access, and to their remaining where it has not. It would seem advisable then, in the first bucking or two, when the cloth is foul, to use the lye considerably below the boiling point; that by this soaking or maceration, the foulness may be entirely discharged, and the cloth quite opened for the speedy reception of the boiling lye in the buckings which follow.

The lyes should likewise be weakened in the first buckings, because then they act only on the more external parts; whereas, when the cloth is more opened, and the field of action is increased, the active powers ought to be too so. For this reason they are at the strongest after some sourings.

The only thing that now remains to be considered, is, the management of the coarse cloth, where boiling is substituted in place of bucking. This species of linen cannot afford the time and labour necessary for the latter operation; and therefore they must undergo a shorter and more active method. As the heat continues longer at the degree of boiling, the lyes used to the coarse cloth must be weaker than those used to the fine. There is not so much danger from heat in the coarse as in the fine cloth, because the former is of a more open texture, and will allow the lye to penetrate more speedily. In the clover kinds, however, the first application of the salts should be made without a boiling heat.

Alternate watering and drying. After the cloth has been bucked, it is carried out to the field, and frequently watered for the first six hours. For if, during that time, when it is strongly impregnated with salts, it is allowed to dry, the salts approaching closer together, and assisted by a greater degree of heat, increasing always in proportion to the dryness of the cloth, act with greater force, and destroy its very texture. After this time, dry spots are allowed to appear before it gets any water. In this state it profits most, as the latter part of the evaporation comes from the more internal parts of the cloth, and will carry away most from those parts. The bleaching of the wax, in a preceding experiment, helps to confirm this; for it seemed to whiten most when the last particles of water were going off.

This continual evaporation from the surface of the cloth shows, that the design of the operation is to carry off somewhat remaining after the former process of bucking. This appears likewise from a fact known to Bleaching all bleachers, that the upper side of cloth, where the evaporation is strongest, attains to a greater degree of whiteness than the under side. But it is placed beyond all doubt by experiment, which shows, that cloth turns much lighter by being exposed to the influence of the sun, air, and winds, even though the faults have been washed out of it.

What, then, is this substance? As we have discovered in the former section, that the whitening, in the operation of bucking, depends on the extracting or loosening the heavy oil and solid particles of the flax; it appears highly probable, that the effects of watering, and exposition to the sun, air, and winds, are produced by the evaporation of the same substance, joined to the faults, with which composite body the cloth is impregnated when exposed on the field. That these faults are in a great measure carried off or destroyed, appears from the cloth's being allowed to dry without any danger after the evaporation has gone on for some time. "If we can show (says Dr Home) that oils and faults, when joined together, are capable of being exhaled, in this manner, by the heat of the atmosphere, we shall reduce this question to a very great degree of certainty."

"September 10. I exposed in a south-west window half an oz. of Caustic soap, sliced down and watered. September 14. When well dried, it weighed but 3 dr. 6 gr. September 22. It weighed 2 dr. 2 gr. September 24. It weighed 1 dr. 50 gr. It then seemed a very little whiter; but was much more mucilaginous in its taste, and had no degree of saltness which it had before.

"It appears from this experiment, that soap is so volatile, when watered, and exposed to air not very warm, that it loses about half its weight in 14 days. The same must happen to the saponaceous substance, formed from the conjunction of the alkaline salts, heavy oil, and earthy particles of the flax. The whole design, then, of this operation, which by way of pre-eminence, gets the name of bleaching, is to carry off, by the evaporation of water, whatever has been loosened by the former process of bucking.

"Against this doctrine there may be brought two objections, seemingly of great weight. It is a general opinion amongst bleachers, that linen whitens quicker in March and April than in any other months; but as the evaporation cannot be so great at that time as when the sun has a greater heat; hence the whitening of cloth is not in proportion to the degree of evaporation; and therefore the former cannot be owing to the latter. This objection vanishes, when we consider, that the cloth that comes first into the bleachfield, in the spring, is closely attended, having no other to interfere with it for some time; and as it is the whitest, gets, in the after-buckings, the first of the lye; while the second parcel is often bucked with what has been used to the first. Were the fact true, on which the objection is founded, this would be a sufficient answer to the objection. But it appears not to be true, from an observation of Mr John Christie, That cloth laid down in the beginning of June, and finished in September, takes generally less work, and undergoes fewer operations, than what is laid down in March, and finished in June.

"The other objection is, That cloth dries much faster in windy weather than in calm sun-shine; but it does not bleach so fast. This would seem to show, that the sun has some particular influence independent on evaporation. In answer to this objection, let it be considered, that it is not the evaporation from the surface, but from the more internal parts, that is of benefit to the cloth. Now, this latter evaporation must be much stronger in sunshine than in windy weather, on account of the heat of the sun, which will make the cloth more open; while the coldness of windy weather must shut it up, so that the evaporation will all be from the surface. Clear sun-shine, with a very little wind, is observed to be the best weather for bleaching; a convincing proof that this reasoning is just.

"It would seem to follow as a corollary from this reasoning, that the number of waterings should in general be in proportion to the strength of the lye; for the stronger the lye is, the more there is to be evaporated; and the greater the danger, in case the cloth should be allowed to dry. But there is an exception to this general rule, arising from the consideration of another circumstance. It is observed, that cloth when brown, dries sooner than when it becomes whiter, arising from the closeness and oiliness which it then has not allowing the water a free passage. Perhaps that colour may retain a greater degree of heat, and in that way assist a very little. Cloth therefore, after the first buckings, must be more carefully watered than after the last.

"It follows likewise from this reasoning, that the foil of the bleachfield should be gravelly or sandy, that the water may pass quickly through it, and that the heat may be increased by the reflection of the foil, for the success of this operation depends on the mutual action of heat and evaporation. It is likewise necessary that the water should be light, soft, and free from mud or dirt, which not being able to rise along with the water, must remain behind. When there is much of this, it becomes necessary to rinse the cloth in water, and then give it a milling, to take out the dirt; else it would be fixed in the cloth by the following bucking, as it is not soluble by the lye.

"This operation has more attributed to it by bleachers than it can justly claim. The cloth appears, even to the eye, to whiten under these alternate waterings and dryings; and these naturally get the honour of it, when it more properly belongs to the former operation. Here lies the fallacy. Alkaline faults give a very high colour to the decoctions or infusion of vegetables. This is probably owing to the solution of the oleaginous colouring particles of the plant; which particles, being opened and separated by the faults, occupy a greater space, and give a deep colour to the liquor. The cloth participates of the liquor and colour. Hence bleachers always judge of the goodness of the bucking by the deepness of its colour. The rule, in general, is good. I observe that in those buckings which continue from the Saturday night to the Monday morning, the cloth has always the deepest colour. When that cloth has been exposed some hours to the influence of the air, these colouring particles which are but loosely attached to it, are evaporated, and the linen appears of a brighter colour. This operation does no more than complete what the former had almost finished. If its own merit were thoroughly known, there would be no occasion to attribute that of another operation to it. Thread, and open cloths, such as diaper, may be reduced to a great degree..." No cloth, as would appear, can attain to a bright whiteness without it.

"Since the only advantage of watering is the removal of the salts, and what they have dissolved, might we not effectuate this by some cheaper and more certain method? For it occupies many hands; and must depend altogether on the uncertainty of the weather; so that in the beginning of the season, the bleacher is often obliged to repeat his buckings without bleaching. We might take out the alkaline salts by acids; but then the other substance would be left alone in the cloth, nor would any washing be able to remove it. Mill-washing appears a more probable method of taking out both salts and oils; and it would seem that this might in a great measure supply the place of watering; but upon trial it does not succeed. Two parcels of linen were managed equally in every other respect, except in this, that one was watered, and exposed to the influence of the air, and the other was only mill-washed. This method was followed until they were fit for scouring. The cloth which had been mill-washed had a remarkable green colour, and did not recover the bright colour of the pieces managed in the common way, until it had been treated like them for a fortnight. The green colour was certainly owing to a precipitation of the sulphurous particles, with which the lye is impregnated, upon the surface of the cloth; owing to the salts being washed off more speedily than the sulphur, to which they are united in the lye. The attachment betwixt these two bodies we know is very loose, and the separation easily made. Evaporation then alone is sufficient to carry off these sulphureous particles."

Souring. It is well known to all chemists, that alkaline salts are convertible, by different methods, into absorbent earths. Frequent solution in water, and evaporation of it again, is one of these. This transmutation then of these salts, which are not volatilized or washed away, must be continually going on in the cloth under these alternate waterings and dryings of the former process; not much indeed after the first two or three buckings; because the salts, not having entered deep into the cloth, are easily washed off, or evaporated. But when they penetrate into the very composition of the last and minutest fibres, of which the first vessels are made, they find greater difficulty of escaping again, and must be more subject to this transmutation. But if we consider the bleaching ashes as a composition of lime and alkaline salts, we must discover a fresh fund for the deposition of this absorbent earth. The common caustic, a composition of this very kind, soon converts itself, if exposed to the open air, into a harmless earthy powder.

Frequent buckings and bleachings load the cloth with this substance. It becomes then necessary to take it out. No washing can do that, because earth is not soluble in water. Nothing but acids can remove it. These are attracted by the absorbent earth, join themselves to it, and compose a kind of neutral imperfect salt, which is soluble in water, and therefore easily washed out of the cloth. The acid liquors commonly used are butter-milk, which is reckoned the best, four-milk, infusion of bran, rye-meal, &c. kept for some days till they sour. Sour whey is thought to give the cloth a yellow colour.

The linen ought to be dried before it is put in the four, that the acid particles may penetrate, along with the watery, through the whole. A few hours after it has been there, air-bubbles arise, the liquor swells, and a thick foam is formed; manifest signs of a fermentation. The following experiment, says Dr Home, shows the degree of heat which attends it.

"May 25. I put a thermometer of Fahrenheit's into some butter-milk, of which the bleachers were composing their fours, and which stood in a vat adjoining to another, where the milk was the same, and the fouring process had been going on for two days. After the thermometer had been 20 minutes in the butter-milk, the mercury stood at 64 degrees. In the fouring vat it rose to 68 degrees. An increase of four degrees shows a pretty brisk intestine motion.

"To what are all these effects owing? To the acetic fermentation going on in those vegetable liquors, whose acids, extricating themselves, produce heat, intestine motion, and air-bubbles. As the change is slow, the process takes five or six days before it is finished. During this time the acid particles are continually uniting themselves to the absorbent earth in the cloth. That this fermentation goes on in the liquor alone, appears from this consideration, that the same effects, viz. air-bubbles, and foam, are to be seen in the butter-milk alone. The only effect then it has is, by the small degree of heat, and intestine motion, which attend it, to affix the junction of the acid and absorbent particles. We shall presently see that this process may be carried on to as great advantage, without any fermentation; and therefore it appears not absolutely necessary.

"When these absorbent particles are fully saturated, the remaining acids may unite with, and have some small effect in extracting the colouring particles. This appears from the two following experiments.

"Sept. 20. A piece of cloth which had been steeped, weighing 41½ gr. was put into a half-pound of butter-milk, whisked, and well foured, by a mixture of water, and by boiling. Sept. 24. When taken out, and washed in water, it appeared a very little whiter. The mineral acids, as will appear afterwards, whiten cloth, even though they are very much diluted.

"Just before the acetic fermentation is finished, the cloth should be taken out; otherwise the foam will fall down and lodge in the cloth, and the putrefaction which then begins will weaken it. This appears from the following experiment.

"Sept. 16. A piece of cloth weighing 42 gr. was laid in butter-milk unwhisked. Novem. 15. The milk had a putrefied smell. The cloth was a little whiter, but very tender; and weighed, when well washed in warm water and dried, 40 gr."

All the fours made of bran, rye-meal, &c. ought to be prepared before use; for by this means so much time will be saved. Besides, when the water is poured upon the cloth and bran, as is done in the management of coarse cloth, the linen is not in a better situation than if it had been taken up wet from the field; and by this means the acid particles cannot penetrate so deep. Again, this method of mixing the bran with the cloth, may be attended with yet worse consequences. All vegetable substances, when much pre- Bleaching, fed, fall into the putrefactive, and not the acetic fermentation. This often happens to the bran preferred between the different layers on the linen, which must weaken the cloth. Hence, all fours should be prepared before the cloth is steeped in them; and none of the bran or meal should be mixed with the cloth.

The fours are used strongest at first, and gradually weakened till the cloth has attained to its whiteness. In the first fourings, there is more of the earthy matter in the cloth, from the many buckings it has undergone, than what there can be afterwards. As the quantity of this matter decreases, so should the strength of the four. There is not, however, the least danger, at any time, from too strong a four.

What is most wanted in this operation is a more expeditious and cheaper method of obtaining the same end. As it takes five or six days, it retards the whitening of the cloth considerably; and as bleachers are obliged to send for milk to a great distance, it becomes very dear. This last consideration makes them keep it too long, that, when used, it can have no good effect; perhaps it may have a bad one.

There is one consideration that may lead us to shorten the time. It is observed, that the fouling process is sooner finished in warm than in cold weather. Heat quickens the fermentation, by aiding the intestine motion. The vats therefore should not be buried in the ground, as they always are, which must keep them cold; there should rather be pipes along the walls of the room, to give it that degree of heat which, on trial, may be found to answer best. There are few days in summer so hot as is necessary; and the beginning and end of the season is by much too cold. That this is no ideal scheme, the following fact is a sufficient proof. There are two vats in Salton bleachfield, adjoining to a partition wall, at the back of which there is a kitchen-fire. In these vats the fouling process is finished in three days, whereas it lasts five or six days in the other placed round the same room.

This improvement, tho' it shortens the time of fouling a very little, yet is no remedy against the scarcity and dearth of milk fours. Such a liquor as would serve our purpose, must be found either among the vegetable acids, which have no further fermentation to undergo, or among the mineral acids. The former are a large class, and contain within themselves many different species; such as the acid juice of several plants, vinegars made of fermented liquors, and acid salts, called tartars. But there is one objection against these vegetable acids; they all contain, along with the acid, a great quantity of oily particles, which would not fail to discolour the cloth. Besides, the demand of the bleachfields would raise their price too high.

The mineral acids have neither of these objections. They are exceedingly cheap, and contain no oil. "I will freely own (says Dr Home), that at first I had no great opinion of success from the mineral, from two reasons; their want of all fermentation, which I then looked on as unnecessary; and their extreme corrosiveness. But the experience of two different summers, in two different bleachfields, has convinced me, that they will answer all the purposes of the milk and bran fours; nay, in several respects be much preferable to them. I have seen many pieces of fine cloth, which had no other fours but those of vitriol, and were as white and strong as those bleached in the common way. I have cut several webs through the middle, and bleached one half with milk and the other with vitriol; gave both the same number of operations, and the latter were as white and strong as the former."

The method in which it has been hitherto used is this. The proportion of the oil of vitriol to the water, with which it is diluted, is half an ounce or at most three quarters, to a gallon of water. As the milk-fours are diminished in strength, so ought the vitriol-fours. The whole quantity of the oil of vitriol to be used, may be first mixed with a small quantity of water, then added to the whole quantity of water, and well mixed together. The water should be milk-warm; by which means the acid particles will penetrate further, and operate sooner. The cloth should then be put dry into the liquor.

It is observed, that this four performs its task much sooner than those of milk and bran; so that Mr John Christie, in making the trial, used to lay the milk-fours 24 hours before the vitriol. Five hours will do as much with this four as five days with the common sort. But the cloth can receive no harm in allowing it to remain for some days in the four; but rather, on the contrary, an advantage. The cloth is then taken out, well rinsed, and mill-washed in the ordinary way.

The liquor, while the cloth lies in this four, is less acid the second day than the first, less the third than the second, and so diminishes by degrees. At first it is clear, but by degrees a mucilaginous substance is observed to float in it, when put into a glass. This foulness increases every day. This substance, extracted by the acid, is the same with what is extracted by the alkaline salts; and blunts the acidity of the former, as it does the alkaline of the latter. Hence the liquor loses its acidity. But as the acid salts do not unite so equally with oily substances as the alkaline do, the liquor is not so uniformly tinged in the former as in the latter case, and the mucous substance prevents itself floating in it.

It is observed, that in the first fouling, which is the strongest, the liquor, which was a pretty strong acid before the cloth was put in, immediately afterwards becomes quite vapour; a proof how very soon it performs its task. But in the following operations, as the linen advances in whiteness, the acidity continues much longer; so that in the last operations the liquor loses very little of its acidity. This happens although the first buckings after the first fourings are increased in strength, while the fours are diminished. There are two causes to which this is owing. The texture of the cloth is now so opened, that although the lyes are strong, the alkaline salts and absorbent earth are easily washed out; and the oily particles are in a great measure removed which help to blunt the acidity of the liquor.

Two objections are made against the use of vitriol-fours. One is, that the process of fouling with milk is performed by a fermentation; and as there is no fermentation in the vitriol-fours, they cannot serve the purpose so well; the other, that they may hurt the texture of the cloth. The answer to the former objection is very short; that the vitriol-fours operate successfully without a fermentation, as experience shows; and therefore in them a fermentation is not necessary. As to the latter objection, that oil of vitriol, being a very corrosive body, may hurt the cloth; that will vanish likewise, when it is considered how much the vitriol is diluted with water, that the liquor is not stronger than vinegar, and that it may be safely taken into the human body.

That it may be used with safety, much stronger than what is necessary in the bleachfield, appears from the following experiment with regard to the stamping of linen. After the linen is boiled in a lye of ashes, it is bleached for some time. After this, in order to make it receive the colour, it is steeped in a four of water and oil of vitriol, about 15 times stronger than that made use of in the bleachfield; for to 100 gallons of water are added two and a half of oil of vitriol. Into this quantity of liquor, made so warm as the hand can just be held in it, is put seven pieces of 28 yards each. The linen remains in it about two hours, and comes out remarkably whiter. The fine cloth often undergoes this operation twice. Nor is there any danger if the oil of vitriol is well mixed with the water. But if the two are not well mixed together, and the oil of vitriol remains in some parts undiluted, the cloth is corroded into holes.

Let us now take a view of the advantages which the vitriol-lours must have over the milk. The latter is full of oily particles, some of which must be left in the cloth; but the case is worse when the fum is allowed to precipitate upon the cloth. The former is liable to neither of these objections.

The common fours halter very fast to corruption; and if, from want of proper care, they ever arrive at that state, must damage the cloth very much. As the milk is kept very long, it is often corrupted before it is used; and without acting as a four, has all the bad effects of putrefaction. The vitriol-lours are not subject to putrefaction.

The milk takes five days to perform its task; but the vitriol-lours do it in as many hours; nay, perhaps as many minutes. Their junction with the absorbent particles in the cloth must be immediate, whenever these acid particles enter with the water. An unanswerable proof that the fact is so, arises from the circumstances which happen when the cloth is first steeped in the vitriol-four; the cloth has no sooner imbibed the acid liquor, than it loses all acidity, and becomes immediately vapid. This effect of vitriol-lours must be of great advantage in the bleachfield, as the bleachers are at present hindered from enjoying the favour by the tediousness of the fouring process. The whole round of operations takes seven days; to answer which they must have seven parcels, which are often mixing together, and causing mistakes. As three days at most will be sufficient for all the operations when vitriol-lours are used, there will be no more than three parcels. The cloth will be kept a shorter time in the bleachfield, and arrive sooner at market.

The milk-fours are very dear, and often difficult to be got; but the vitriol are cheap, may be easily procured, and at any time.

There is yet another advantage in the use of vitriol, and that is its power of whitening cloth. Even in this diluted state, its whitening power is very considerable. We have already seen, that it removes the same colouring particles which the alkaline lyes do. What of it then remains, after the alkaline and absorbent particles are neutralized in the cloth, must act on these colouring particles, and help to whiten the cloth. That this is really the case, appears from the following fact. Mr Christie being obliged to choose 20 of the whitest pieces out of 100, five of the twenty were taken out of seven pieces which were bleached with vitriol.

From both experience and reason, it appears, that it would be for the advantage of our linen-manufacture to use vitriol in place of milk-lours.

Hand-rubbing with soap and warm water, rubbing-boards, starching, and bluing.—After the cloth comes from the fouring, it should be well washed in the washing-mill, to take off all the acid particles which adhere to its surface. All acids decompose soap, by separating the alkaline salts and oily parts from one another. Were this to happen on the surface of the cloth, the oil would remain; nor would the washing-mill afterwards be able to carry it off.

From the washing-mill the fine cloth is carried to be rubbed by women's hands, with soap and water. As the liquors, which are generally employed for fouring, are impregnated with oily particles, many of these must lodge in the cloth, and remain notwithstanding the preceding milling. It is probable, that all the heavy oils are not evaporated by bleaching. Hence it becomes necessary to apply soap and warm water, which unite with, dissolve, and carry them off. It is observed, that if the cloth, when it is pretty white, gets too much soap, the following bleaching is apt to make it yellow; on that account they often wring out the soap.

It is a matter worth inquiring into, whether hard or soft soap is best for cloth. Most bleachers agree, that hard soap is apt to leave a yellowness in the cloth. It is said, that the use of hard soap is discharged in Holland. As there must be a considerable quantity of salt in this kind, which is not in the soft, and as this salt appears prejudicial to cloth, the soft soap ought to be preferred.

The management of the coarse cloth is very different, in this operation, from fine. Instead of being rubbed with hands, which would be too expensive, it is laid on a table, run over with soap, and then put betwixt the rubbing-boards, which have ridges and grooves from one side to another, like teeth. These boards have small ledges to keep in the soap and water, which saves the cloth. They are moved by hands or a water-wheel, which is more equal and cheaper. The cloth is drawn by degrees through the boards, by men who attend; or which is more equal and cheaper, the same water-wheel moves two rollers, with ridge and groove, so that the former enters the latter, and by a gentle motion round their own axis, pull the cloth gradually through the boards.

This mill was invented in Ireland about thirty years ago. The Irish bleachers use it for their fine as well as coarse cloth. These rubbing-boards were discharged some years ago in Ireland, by the trustees for the manufactures of that country, convinced from long experience of their bad effects. But as proper care was not taken to instruct the bleachers by degrees in a safer method, they continued in the old, made a party, and kept possession of the rubbing-boards. There were considerable improvements made in them in this country; such such as the addition of the ledges, to keep the cloth moist; and of the rollers, which pull the cloth more gradually than men's hands. These improvements were first made in Salton bleachfield.

The objections against these rubbing-boards are unanswerable. By rubbing on such an unequal surface, the solid fibrous part of the cloth is wore; by which means it is much thinned, and in a great measure weakened before it comes to the market. As a proof of this, if the water which comes from the cloth in the rubbing-boards be examined, it will be found full of cottony fibrous matter. These boards give the cloth a cottony surface, so that it does not keep long clean. Again, they flatten the threads, and take away all that roundness and firmness which is the distinguishing property of cloth bleached in the Dutch method.

For these reasons they must be very prejudicial to fine cloth, and should never be used in bleaching it. As they seem to be in some measure necessary to lessen the expense of bleaching coarse linen, they ought never to be used above twice, or thrice at most. They might be rendered much more safe, by lining their insides with some soft elastic substance, that will not wear the cloth so much as the wooden teeth do. Mr Christie at Perth has lined his boards with short hair for some years past, and finds that it answers very well.

After the coarse cloth has undergone a rubbing, it should be immediately milled for an hour, and warm water poured now and then on it to make it lather. This milling has very good effects; for it cleans the cloth of all the dirt and filth which the rubbing-boards have loosed, and which, at the next boiling, would discolour the cloth. Besides, it is observed, that it makes the cloth less cottony, and more firm, than when whitened by rubbing alone.

The last operation is that of starching and bluing. It often happens, that the cloth, when exposed to the weather to be dried after this operation, gets rain: which undoes all again, and forces the bleacher to a new expense. To remedy this inconvenience, Mr Christie, some years ago, invented the dry-house, where the cloth may be dried, after this operation, in any weather. This invention meets with universal approbation.

A method of bleaching safely with lime.—Dr Home has found by repeated trials, that alkaline salts added to lime, diminish its power of weakening and corroding cloth; and that in proportion to the quantity of these salts added to the lime. This composition, as it is not so dangerous as lime alone, so it is not so expeditious in whitening. When equal parts of each are used, the whitening power is strong, and the weakening power not very considerable; so that they might be used with safety to bleach cloth, in the proportion of one part of lime to four of pure alkaline salts. This fully accounts for an observation made by all bleachers, that the bleaching salts, when mixed together, operate safer and better than when used separately. For the corrosive power of the Mucovoy, Marcroft, and Caffhub ashes, is corrected by the pearl ashes, and the whitening quality of the latter is increased by that of the former.

There is not a more corroding substance, with regard to animals, than alkaline salts and lime joined together, especially when fused in the fire. This is the composition of the common caustic. But lime, and lime-water alone, preserve animal substances in a sound entire state. It appears then surprising, that salts and lime should be found so little destructive of cloth, when lime, or lime-water alone, destroys it so remarkably. But that this is a fact, is made evident by many experiments, and has been practised both with success and safety, by a bleacher who gives the following account of his method of bleaching with lime.

"First (says he) I steep the cloth in warm water for 24 hours; then clean it in a washing-mill, of all the dressing, or fowen, as the vulgar term it. Afterwards I buck cloth with cow-dung and water, and bleach it with this for three days; then clean it again, and boil it with a lye made of Caffhub ashes. A pound to each piece of 18 or 20 yards long is sufficient. This I do twice, as no lime ought to be given to cloth before it is a full third whitened; as it by no means advances the whitening of the cloth, but, on the contrary, contracts it: For, instead of loosening the oil and dirt in the cloth, when brown, it rather fixes them; just as when fine cloth is bucked with over-warm lyes in the first buckings. Lime is by no means fit for discharging the oil in the cloth, but for cleansing it of the dead part, commonly called sprat. The cloth, being cleaned, is laid upon a dreaper. It must not be drier before bucking with lime, otherwise it will take in more than can be got out again before the next application: for as I have observed already, that lime is only fit for discharging the dead part, bucking thus wet makes it rest on the outside of the cloth. I take a lippy of the finest and richest powdered lime that can be got, of the brightest white colour, as poor lime does more hurt than good, to thirty pieces of the above length; and make a cold lye of it, by stirring and pouring water off the lime, until all be dissolved but the dregs, which is thrown away: then I add a little soap, which makes the lye have the nearest resemblance to milk that breaks in boiling, of anything I can think of; for this soap blunts the hotness of the lime. Then I take the cloth and dip it in the lime-lye, and that moment out again, and lay it on a dreaper until it be bucked; then put it on the field, watering it carefully; for if allowed to dry, it is much damaged. This is done always in the morning; as it cannot be done at night, in regard of the hot quality of the lime, which soon heats the cloth and tenderizes it. If a hot sun-shine follows, it has great effect; for lime is just like all other materials for bleaching, that have more or less effect according as the weather is good or bad. I take it up the second day after bucking, and give it a little milling, or hand-rubbing, or bittling, commonly called knocking; and lay it on the field again, watering it carefully as before. The effect is more visible the second than the first day. As all cloth when limed should have a great deal of work, otherwise more than half the effect is lost; and not only that, but a great deal of labour and pains is requisite to take the lime out of the cloth again; it must never be exposed on the Sabbath day, but carefully kept wet always while used in this way. Thus bucking for three or four times at most, is sufficient for any cloth, except that made of flax pulled either over-green, or which grows in a doughty season, or perhaps not so well heckled as it should be. This sort occasions great trouble and expense to the bleacher. But the most bleaching most effectual and expeditious way I ever found for this kind was, after boiling, to take a little of the warm lye, and mix a very small quantity of lime with it, and draw the cloth through that as hot as possible, and put it on the field directly, watering it carefully. This will clean it of the sprat surprisingly. Then I boil it with pearl ashes, and give it the last boil with soap.

"There are innumerable mistakes in the use of lime committed by the vulgar, who are ignorant of its quality and effects. They know only this in general, that it is a thing which whitens cloth cheap, and is easy purchased; therefore they will use it. Some of them begin whitening of their cloth with it, which I have already observed to be wrong, and given reasons for it, and continue it until the cloth is bleached; give it a boil or two at most, and then wash it up while the gross body of the lime is in the substance of the cloth. This makes limed cloth easily distinguishable from unlimed, as the former has a yellowish colour, and is full of a powder. Besides, as lime is of a very hot corroding nature, it must by degrees weaken the cloth. The bad effects of this substance do not end here. When the cloth is put on board, it contracts a dampness, which not only makes it yellow, and lose any thing of colour it has, but directly rots it. And although it should escape this, which it is possible it may, by a quick and speedy passage; yet whenever it is put in any warehouse, it will meet with moisture there, especially if the winter season should come on before it is disposed or made use of. These I take to be the principal reasons for so much complaint in bleaching with this material."

The whole art and safety in using the lime, according to this method, depends on the junction of the alkaline salts, during the bucking, to the particles of lime which were on the surface of the cloth.

As the operation of bleaching depends on the extraction of a certain quantity of phlogistic matter from the cloth, it is natural to suppose that it might be accelerated by rendering the alkali very caustic. Thus the salt would be entirely freed from the encumbrance of fixed air, with which in the usual experiments of chemistry it appears to have a greater affinity than with oil; for soap may be partially decomposed by fixed air, nor can it be prepared without an exceedingly caustic alkaline lye. In this light the matter has appeared to some very eminent chemists; and Dr Black thought it of importance sufficient to publish printed directions to the practical bleachers how to render their alkali sufficiently caustic with lime, and at the same time recover it from the chalky residuum with as little loss as possible. This method has accordingly been tried; but is not found altogether to answer the sanguine expectations at first raised by the proposal. It is found that in the large way of operating, fixed alkali quits the fixed air to unite with the oily or other matter to be extracted from the cloth. The only advantage therefore to be gained by Dr Black's improvement is, that the action of the alkali is thus quickened, and some quantity of fuel saved; but this is not, by the bleachers, reckoned an equivalent to the trouble of rendering the alkali caustic, unless in places where fuel is very scarce.

The use of acids in bleaching was formerly in a great measure unaccounted for; but from the late discoveries concerning the use of dephlogisticated spirit of Bleaching, salt in this art, it appears probable that they act by means of the dephlogisticated air they contain. This, however, is not always the case; for silk is rendered yellow by the action of dephlogisticated air, though rendered white by the action of the volatile sulphureous acid, which undoubtedly contains a portion of this kind of air, though much less than the concentrated vitriolic. The nitrous acid, which contains a great quantity of dephlogisticated air, likewise communicates a yellow colour to silk; and indeed seems very much inclined to produce this colour upon all the substances it touches. At any rate, its price would be a sufficient objection against its use in bleaching. The spirit of salt in its common state is said by M. Berthollet to be used with success by some bleachers in France instead of the vitriolic; but such experiments as have been made upon it in this country have not answered the purpose. The new method of bleaching is founded upon that remarkable property which dephlogisticated spirit of salt possesses, of destroying vegetable colours; and various attempts have been made to introduce it into practice, though in this country the difficulties or disadvantages attending it have prevented it from coming into general use. M. Scheele was the inventor of this substance; but M. Berthollet seems to have been the first who attempted to apply it to the practice of bleaching. In consequence of his observations, a treatise has appeared on the new method of bleaching, collected and translated from his works by Mr Kerr surgeon in Edinburgh; of which the following is an abridgment.

1. M. Berthollet having procured the dephlogisticated spirit in as strong and concentrated a state as he could, immersed it into thread and cloth; which by that means were considerably whitened. In a short time the liquor seemed to lose its strength; upon which it was poured off, and more put in its place; and so on until the substance immersed became perfectly white. Thus, however, the process was not only very expensive, but the stuff was considerably injured; sometimes even losing its cohesion altogether, so that there was a necessity for trying some other method.

2. Using a diluted spirit, he succeeded perfectly in rendering the cloths completely white; but by keeping them for some time, or exposing them for a little to the action of an alkaline lye, they became again brown or yellow.

3. On considering the process of bleaching in the common method, he found that the action of the sun and air are subservient to bleaching only as they prepared the colouring particles for being dissolved and separated by alkaline lixivia. To investigate this subject, he examined the nature of the dews, both such as are precipitated from the atmosphere and those which transpire from vegetables. Both of these were found so strongly impregnated with dephlogisticated air, that they destroyed the colour of paper when faintly tinged with turpentine. Hence our author observes, that it is by no means improbable that the ancient prejudices concerning May-dews might have arisen from some observations analogous to this, more especially as in that month the transpiration of plants is extremely copious.

4. By imitating with the dephlogisticated marine acid and alkaline lye the common process of bleaching, he succeeded Bleaching succeeded in making a perfect and permanent white. For this purpose an alkaline lixivium was employed alternately with the deplogisticated marine acid; the latter being no longer used in a concentrated state. Thus he avoided both the inconvenience arising from the suffocating smell of the liquid, and that of its destroying the texture of the stuff immersed in it.

5. The cloth is prepared for bleaching in this manner by steeping it 24 hours in water, to extract the dressing it receives from the weaver: a little old lye, which has already lost the greatest part of its strength in other processes, may be used with advantage. It is next to be exposed once or twice to the action of some good fresh alkaline lye; in order to separate by means of this cheaper liquid all the colouring matter which it can extract, and thereby save the deplogisticated acid.

6. The stuff must now be carefully washed with water to separate any remains of the lye which might adhere to it and weaken the action of the liquor. It is then to be disposed of in wooden troughs, so that the deplogisticated acid may pass freely through every part of it; to allow which, it must lie quite loose, without being tightened or strained in any part. All these troughs ought to be constructed entirely of wood without any iron, as that would easily be corroded and stain the cloth.

7. The first immersion in the deplogisticated acid is to continue 3 hours; after which the cloth is to be removed, and the liquor wrung out of it. It must then be washed a second time with alkaline lye; which being also washed out, it is to be again immersed in deplogisticated acid.

8. The second immersion in the acid is to continue only about half an hour; after which it is to be taken out and wrung as before. The same liquor may serve for several immersions; only when it appears to be much exhausted, it is to be restored by an addition of fresh liquor.

9. After the cloth seems to be sufficiently whitened, excepting only some few black threads and the selvages, it is to be filled with black soap, and strongly rubbed for some time; after which it is to be again washed in alkaline lye, and receive another immersion in the acid liquor.

10. It has not yet been determined what number of immersions in the acid are necessary to whiten linen cloth, though our author supposes from six to eight to be sufficient for the purpose.

Method of preparing the deplogisticated acid.

11. To prepare the deplogisticated acid, M. Berthollet recommends six ounces of black manganese finely powdered, 16 ounces of sea-salt likewise in powder, and 12 ounces of concentrated vitriolic acid diluted with eight ounces of water; though the quantity of this salt must be variable according to the strength of the acid and the dryness of the salt. If the manganese is impure, its quantity is to be augmented in proportion to the supposed impurity; and it is known whether a sufficient quantity has been employed, by a portion remaining behind and retaining its black colour. When the materials are prepared, the manganese and common salt, both reduced to fine powder, must be mixed accurately together, and put into the distilling vessel placed in a sand-bath; the vitriolic acid diluted with water and allowed to cool is then to be poured upon them, and the junctures exactly luted. The receiver may be of wood covered in the inside with wax, and of a very large size; for the gas is absorbed in proportion to the surface of the water it acts upon. Our author describes an apparatus rather complicated, and which our limits will not allow us to describe in this place, especially as the preparation of this liquid is not as yet so generally practised that it can be determined how far one apparatus is preferable to another. The requisites are, that the receiver should not only be capacious but broad, in order that the gas, which is very volatile, may meet with a large surface of water to absorb as much of it as possible. It is very improbable, however, that all the gas can be absorbed by a single receiver; let us make it as large as we will; for which reason it will be proper to have several of them connected with each other by glass tubes, so that what escapes from one may be absorbed by another. Thus we are sure of having the water fully impregnated with the gas; though we cannot by any means concentrate this liquid like the mineral acids. By means of condensing engines, indeed, a greater quantity of it might be forced into the water than it can naturally contain; but this could answer no useful purpose; for the moment that a bottle containing such liquor was opened, the superfluous gas would fly off with violence and danger to the person who opened it. The bottles themselves would also be liable to burst on every slight alteration of temperature in the atmosphere. It is proper therefore not to attempt the preparation of the liquor in any great degree of strength; though this is indeed attended with a very considerable inconvenience, viz. the difficulty of transporting it from the place where it is prepared to the bleachfield, on account of the great bulk and weight of it. M. Berthollet proposes to have it made at the place where the cloth is to be bleached; and so near, that the deplogisticated spirit of salt might be conveyed by spouts to the troughs which contain the cloth. This, however, must in many cases be impracticable, unless we suppose the generality of bleachers to be possessed of a skill in managing chemical operations which at present they have not. When great quantities of liquor are to be brought from distant places, however, it must undoubtedly be a great discouragement, especially if the best methods have not been used in the preparation so that the liquor could not be afforded at a very low price.

It would add much to the importance of this new method if a comparative estimate of the expenses of this method and the old one were fairly laid before the public; thereto and the preference in this respect appeared justly due determined to the former. This hath not yet been done; nor even the first and most essential step towards it taken, viz. determining how much stuff a certain quantity of deplogisticated spirit of salt will whiten. From such experiments as we have made on the subject, it is probable that the acid drawn from one pound of salt will whiten four of linen cloth without any addition.—This may seem a small expense; but if we consider the vitriolic acid to be made use of, and that the residuum is useless, it would soon be found very considerable. Glauber's salt may indeed be prepared from the residuum of the distillation; but so much of that article is prepared otherwise, that at present the making of it is no object. M. Berthollet mentions the separation of the mineral alkali from the residuum; and says he has received some instructions on this head from M. Morveau and others, but conceals them on account of their being communicated as secrets. Under the article Chemistry, we have taken notice that some celebrated chemists assert that the calces of lead, or lead itself, will decompose sea-salt, and thus afford an easy method of procuring the mineral alkali. On this principle indeed attempts have been made to procure it, but hitherto without success; and from such experiments as we have made it seems to be totally impracticable. The method of decomposing Glauber's salt and other vitriolic salts by means of charcoal, described under the article Chemistry, p. 716, is the only one that seems to promise success. The difficulty here is, that the salt is converted into an heap sulphuris, which cannot be decomposed but by means of an acid. A method of applying ferroil for this purpose has lately been tried with great probability of success. The particulars hitherto discovered concerning this method are, 1. Sea-salt yields one half its weight of pure alkali. 2. From 20 to 25 pounds of fresh ferroil leaves are to be used for every pound of sea-salt. 3. The plant is easily cultivated, yields three crops annually if properly managed, and is superior in acidity to its cultivated state to the wild ferroil. The above calculation was made with wild ferroil. 4. An acre of ground will produce as much ferroil as is sufficient for making from a ton to a ton and an half of alkali. It will not thrive except in moist ground. From these particulars it is probable, that by combining the process of making dephlogisticated spirit of salt with that of preparing the mineral alkali, bleaching might be performed at an easier and cheaper rate than has yet been done; though even here there is some doubt, that without an encouragement from government by taking off the duties from salt and sulphur used in the different operations, a project of this kind might miscarry, to the great detriment of the individual who should attempt it. The reason of such difficulty in the new method of bleaching is, that little or none of the alkali commonly used can be saved. The air also and light of the sun, which in the common way is had for nothing, must in the new way be bought at a certain price. The only advantage therefore is, that in the new method, a considerable portion of time is saved. Hence it is impossible to make an exact comparative calculation of the expense of both methods, without estimating how much labour is saved in the new way. If the price of the labour saved exceeds that of the dephlogisticated spirit of salt, there is no doubt that the use of it will be attended with profit, but not otherwise. It is asserted by M. Berthollet, that in the new way of bleaching, the texture of the cloth is less hurt than in the old one: this too must be reckoned an advantage; though by the bleachers, and indeed by the public in general, it will probably be overlooked, unless they are induced by the cheapness to prefer the new to the old method.

With regard to the various methods of bleaching with lime described in the former part of this treatise, we cannot help remarking, that from such experiments as we have tried on the subject, this substance seems to possess no power whatever of whitening cloth; on the contrary, in all cases where we either tried it ourselves or saw it tried by others, it manifestly prevented the effect of the sun and air in a remarkable degree. When alkali is mixed with it, we are not to ascribe the effect to the lime, but to the alkali; for by the attraction of fixed air from the salt the lime is converted into chalk and becomes wholly inert, while the alkali has its activity augmented by being rendered caustic. Lime-water is totally insignificant unless we put the cloth with it into a close vessel; for lime-water when exposed to the atmosphere instantly loses its activity, the lime being converted into mild calcareous earth, and falling in that state to the bottom. The reason of its destroying the cloth is supposed to be its retaining a quantity of moisture among the threads, so that it never allows the cloth to dry thoroughly: to prevent which, it has been recommended to put the limed cloth through a weak solution of salt, which would no doubt answer the purpose of dissolving the calcareous earth; but when we consider that the lime is a substance, if not pernicious, at least totally useless, it ought certainly to be discouraged as much as possible in the practice of bleaching.

Bleak, in ornithology. See Cyprinus.

Bleachingly, a town of Surry in England, which sends two members to parliament, and the bailiff who returns the members is chosen annually at the lord of the manor's court. The town stands on a hill, and has a fine prospect as far as the South Downs in Sussex. W. Long. O. 15. N. Lat. 51. 20.