grows in warm climates. Cottons differ principally in the length of their filaments, their fineness, strength, and color. This substance has different shades, from a deep yellow to a white. The most beautiful is not always the whitest; it is necessary to bleach it, by processes similar to those employed in the bleaching of linen. Or, instead of these, oxygenated muriatic acid may be employed; and a more beautiful white thus produced, than by the ordinary way of bleaching. M. Berthollet succeeded in bleaching the yellow cotton of St. Domingo, which very obstinately retains this bad color. But, that cotton may be disposed to receive the dye, it must undergo scouring. Some boil it in sour water, but more frequently alkaline lie is used; the cotton must be boiled in it for two hours, and then wrung out; after which it must be rinsed in a stream of water, till the water comes off clear; it must then be carefully dried. The cotton stuffs, which are to be prepared, must be soaked for some time in water, mixed with at most one-fiftieth of sulphuric acid; after which, they must be carefully washed in a stream of water, and dried. M. Berthollet has observed, that the acid which had been used in this operation, had taken up a quantity of calcareous earth and iron, which would have injured the colors very much. Aluming and galling are generally employed in the dyeing of cotton and linen. In the preparation with alum, about four ounces of it are required to each pound of stuff; it must be dissolved with the precautions abovementioned. Some add a solution of soda in the proportion of one-sixteenth of the alum; others a small quantity of tartar and arsenic. The thread is well impregnated by working it pound by pound in this solution; it is then put altogether into a vessel, and what remains of the liquor is poured upon it. This is left for twenty-four hours, and then removed to a stream of water, where it remains for about two hours, to extract a part of the alum, and is then washed. Cotton, by this operation, gains about one-fortieth of its own weight.

100. In the operation of galling, it is usual to employ different quantities of galls or other astringents, according to their quality, or the effect to be produced. Powdered galls are boiled for about two hours, in a quantity of water proportioned to that of the thread to be galled; the liquor is then allowed to cool to a temperature which the hand can bear, after which it is divided into a number of equal parts, that the thread may be wrought pound by pound; and what remains is poured upon the whole together. It is then left for twenty-four hours, when intended for black, but for other colors twelve or fourteen hours are sufficient. It may then be wrung out, and carefully dried. When stuffs are galled, which have already received a color, the operation is to be performed in the cold, that the color may suffer no injury. M. Berthollet found that cotton which had been alumed, acquired more weight in the galling than that which had not undergone that process; although alum adheres but in a small quantity to cotton, it communicates to it a greater power of combining, both with the asVOL. VII.

tringent principle and with the coloring particles of different substances.

OF FLAX.

101. Flax must undergo several preparations before it be fit to receive the dye. Of these, the watering is an operation of much consequence, from its influence on the quality and quantity of the product, and from its deleterious effects on the air. In this operation, a glutinous juice, which holds the green coloring part of the plant in solution, undergoes a greater or less degree of decomposition, according to the mode of conducting the operation. This matter seems to resemble the glutinous part, that is held dissolved in the juice procured from green plants by pressure, which is separated along with the coloring particles by a heat approaching to that of ebullition, which becomes putrid, and which affords ammonia by distillation; but it is probable, that water alone cannot sufficiently separate it from the cortical parts: whence the hemp, which has been watered in too strong a current, is deficient in its softness and pliability, &c. But if the water employed be stagnant and putrid, the hemp acquires a brown color, loses its firmness, and emits highly noxious vapors. This process is therefore performed to the greatest advantage, in watering pits situated on the banks of rivers, where the water may be changed often enough to prevent a putrefaction, that would injure the hemp, and be prejudicial to the workmen; yet not so often as to hinder the degree of putrefaction which is necessary to render the water capable of dissolving the glutinous substance. To prepare flax for the dye, it must also be subjected to the operations of scouring, aluming, and galling, in the same manner as cotton.

PART II.

THE PRACTICE OF DYEING.

102. Before we proceed to give directions for the various processes to be observed in the practice of dyeing, we shall take a brief view of M. Berthollet's observations on dyeing operations in general, which cannot fail to be interesting to the practical dyer.

103. It may be regarded,' says he,' as a general principle, that processes performed in a great manufactory are more advantageous than those which are insulated, since, from the subdivision of labor, each workman, occupied with a single object, acquires cererity and perfection in his employment, by which means the saving of time and labor becomes very considerable.

104. This principle is particularly applicable to the art of dyeing, as the preparation which remains after one operation may often be advantageously employed in another. A bath from which the coloring matter has been nearly extracted in the first operation may be used as a ground for other stuffs, or, with the addition of a fresh portion of ingredients, may form a new bath. The galls which have been applied to the galling of silk may answer a similar purpose for cotton or wool. From this it is evident that the limitations under which the art of dyeing labors

2 Q

in some countries must tend to obstruct its progress and improvement.

105. A dye-house should be situated as near as possible to a stream of water, and should be spacious and well lighted. It should be floored with lime and plaster; and proper means should be adopted to carry off water or spent baths by forming channels or gutters, so that every operation may be conducted with the greatest attention to cleanliness.

106. The size and position of the boilers are to be regulated by the nature and extent of the operations for which they are designed. Excepting for scarlet and other delicate colors, in which tin is used as a mordant, in which case tin vessels are preferable, the boilers should be of brass or copper. Brass, being less apt than copper to be acted on by means of chemical agents, and to communicate spots to the stuffs, is fitter for the purpose of a dyeing vessel. It is scarcely necessary to say that it is of the greatest consequence that the coppers be well cleaned for every operation; and that vessels of a large size should be furnished at the bottom with a pipe and stop-cock for emptying them; there must also be a contrivance above each copper to support the poles for the purpose of draining the stuffs which are immersed, so that the liquor may fall back into the vessel, and prevent waste.

107. Dyes for silk, where a boiling heat is not necessary, are prepared in troughs or backs, which are long copper or wooden vessels. The colors which are used for silk are extremely delicate. They must therefore be dried quickly, that they may not be long exposed to the action of the air, and that there may be no risk of change. For this purpose, it is necessary to have a drying room heated with a stove. The silk is stretched on a moveable pole, which by the dyers is called a shaker. This is hung up in the heated chamber, and kept in constant motion to promote the evaporation.

108. For pieces of stuffs, a winch or reel must be used; the ends of which are supported by two iron forks which may be put up at pleasure in holes made in the curb on which the edges of the copper rest. The manipulations in dyeing are neither difficult nor complicated. Their object is to impregnate the stuff to be dyed with the coloring particles, which are dissolved in the bath. For this purpose, the action of the air is necessary, not only in fixing the coloring particles, but also in rendering them more vivid; while those which have not been fixed in the stuff are to be carefully removed. In dyeing whole pieces of stuff, or a number of pieces at once, the winch or reel mentioned above must be employed One end of the stuff is first laid across it, and, by turning it quickly round, the whole passes successively over it. By turning it afterwards the contrary way, that part of the stuff which was first immersed will be the last in the second immersion, and by this means the coloring matter will be communicated as equally as possible.

109. In dyeing wool in the fleece, a kind of broad ladder with very close rounds, called by the dyers of this country a scraw, or scray, is used. This is placed over the copper, and the wool is

put upon it for the purpose of draining and exposure to the air, or when the liquor is to be changed.

110. To separate the superabundant coloring particles, or those which have not been fixed in the stuff, after being dyed, it must be wrung out. This operation is performed with a cylindrical piece of wood, one end of which is fixed in the wall, or in a post. This operation is often repeated a number of times successively, for the purpose of drying the stuffs more rapidly, and communicating a brighter lustre. When, after a certain quantity of fresh ingredients is added to a liquor, and it is stirred about, it is said to be raked, because it is mixed with the rake. In dyeing, one color is frequently communicated to stuffs, with the intention of applying another upon it, and thus a compound color is produced. The first of these operations is called giving a ground. When it is found necessary to pass stuffs several times through the same liquor, each particular operation is called a dip. A color is said to he rosed, when a red color, having a yellow tinge, is changed to a shade inclining to a crimson or ruby color; and the conversion of a yellow red to a more complete red, is called heightening the color.

111. In addition to these general remarks, we might give more minute details of the different operations which are employed in dyeing; but, as we cannot presume that they would be of much advantage to the practical dyer, we shall not indulge in useless description. Although the manipulations of dyeing are not very various, and appear extremely simple, they require very particular attention, and an experienced eye, in order to judge of the qualities of the bath, to produce and sustain the degree of heat suited to each operation; to avoid all circumstances that might occasion inequalities of color, to judge accurately whether the shade of what comes out of the hath suits the pattern, and to establish the proper gradations in a series of shades.

112. We shall here make a few observations on the qualities and effects of different kinds of water, which may be considered as one of the most essential agents in the art of dyeing. It is almost unnecessary to remark that water which is muddy, or contains putrid substances, should not be employed; and, indeed, no kind of water which possesses qualities distinguished by the taste, ought to be used. Water which holds in solution earthy salts, has a very considerable ac tion on coloring matters, and it is chiefly by means of these salts. Such, for instance, are the nitrates of lime and magnesia, muriate of lime and magnesia, sulphate of lime, and carbonate of lime and of magnesia.

113. These salts, which have earthy bases, oppose the solution of the coloring particles, and by entering into combination with many of them cause a precipitation, by which means the color is at one time deeper, and at other times duller than would otherwise be the case. Waters impregnated with the carbonates of lime and magnesia, yield a precipitate when they are boiled; for the excess of carbonic acid which heli them in solution is driven off by the heat; the earths are thus precipitated, and adhering to the stuffs

to be dyed, render them foul, and prevent the coloring matter from combining with them.

114. It is of much consequence to be able to distinguish the different kinds of water which come under the denomination of hard-water, that they may be avoided in the essential operations of dyeing; but to detect different principles contained in such waters, and to ascertain their quantity with precision, require great skill, and very delicate management of chemical operations, which the experienced chemist only can be supposed to possess.

115. One of these tests is the soap solution, by which it may be discovered whether water contain so large a portion of any of these saline matters as may be injurious to the processes. Salts which have earthy bases have the property of decomposing soap by the action of double affinity. The acid of the salt combines with the alkali of the soap, and remains in solution, while the earth of the salt and the oil of the soap enter into combination, and form an earthy product which is insoluble in water, and produces the curdling appearance which is the consequence of this new combination. Water, then, which is limpid, which has no perceptible taste or smell, and has the property of dissolving soap without decomposition, is sufficiently pure for the processes of dyeing. All waters which possess these qualities will be found equally proper for these purposes.

116. But, as it is not always in the power of the dyer to choose pure water, means of correcting the water which would be injurious, and particularly for the dyeing of delicate colors, have been proposed. Water in which bran has been allowed to become sour, is most commonly employed for this purpose. This is known by the name of sours, or sour water. The method of preparing sour water is this: Twenty four bushels of bran are put into a vessel that will contain about ten hogsheads. A large boiler is filled with water, and when it is just ready to boil, it is poured into the vessel. Soon after the acid fermentation commences, and in about twenty hours the liquor is fit for use. Water which is impregnated with earthy salts, after being treated in this way, forms no precipitate when boiled.

117. Mucilaginous plants are sometimes boiled in the water for the purpose of correcting it, when a froth forms that is to be carefully skimmed off as it rises. The mucilage coagulates, carrying with it the earths which separate on the volatilisation of the carbonic acid, as well as those that are merely mixed with the water and which render it turbid.

The salts, however, which have an earthy base, and which are in general injurious to dyeing, do, in certain cases, serve to modify the colors when the object of the dyer is to obtain deep shades. In this way, for example, a crimson hue is given to the color produced by cochincal.

OF DYEING BLACK.

118. We now proceed to give an account of the most useful and advantageous processes for dying different colors, and begin with the method of dying black.

It has been justly observed, by an able writer on this subject, that absolute black being a complete privation of all color, can scarcely be ascribed to any body in nature, since it must then become invisible. The color so named, as communicated by dye-stuffs, is, indeed, rather an intense blue or brown, and is generally produced by the union of these coloring matters with a ferruginous mordant, and hence it may not improperly be termed a compound color. The juice of the cashew nut communicates a black that will not wash out, and which resists boiling with soap or alkalis. The anacardium occiden'ale and the toxicodendron afford a durable dye, but it is of a brownish hue. The juice of the sloe affords a pale tint of a brownish cast, which becomes deeper after having been repeatedly washed with soap, and afterwards wetted with a solution of alkali. On boiling sloes, their juice becomes red, and the red tinge, which in that state it imparts to linen, is converted by washing with soap into a bluish color cf some durability. But these methods of obtaining a black color cannot be employed in dyeing, because these substances are not to be obtained in sufficient quantity, and the black which they afford is not equal to that formed by the common processes. All black colors, therefore, are the effects of combination. To produce them, the black particles formed by the union of the astringent principle with the oxide of iron, held in solution by an acid, are fixed on the stuff that is intended to be dyed.

119. There are very few substances which have the property of producing of themselves a permanent black color. The juice of some plants is found to produce this effect on cotton and linen.

120. When the particles are precipitated from the mixture of an astringent and a solution of iron, they have only a blue color; if they be then left exposed to the air, and moistened with water, their color becomes deeper, but still the blue is distinguishable. The stuff itself then contributes to increase the intensity of the black, whether it be that in this state of combination it undergoes a slight combustion, or that the coloring particles undergo a further degree of combustion, from presenting a larger surface to the air. Without the action of the air, however, a fine black cannot be produced; on which account the operations are performed at different intervals, during which the stuff is taken out of the bath, that it may be exposed to the air. M. Berthollet has ascertained, that black stuffs placed in contact with pure air diminish its volume, and consequently absorb a certain portion of it.

121. Of Dyeing Woollen Black. From the process described by Hellot, woollen cloth, to be dyed black ought to receive the deepest blue tint, or mazarine blue, to be washed in the river as soon as taken out of the vat, and afterwards cleansed by the fulling mill.

For every hundred pounds of stuff, ten pounds of logwood, and ten pounds of galls reduced to powder, are put into a bag, and boiled with a sufficient quantity of water, for twelve hours. A third of this liquor is put into another copper, with two pounds of verdigris. The stuff is im

mersed in this, and continually stirred for two hours. The liquor should be kept hot, but it ought not to boil. At the end of two hours the stuff is taken out, and a similar portion of the liquor is put into the copper, with eight pounds of sulphate of iron. During the solution of the copperas, the fire is diminished, and the liquor is allowed to cool for half an hour, stirring it well the whole time. The remainder is then to be added, and, after making this addition, the bag containing the astringent matters should be strongly pressed, to separate the whole. A quantity of sumach, from fifteen to twenty pounds, is now to be added, and the liquor is just raised to the boiling temperature; and when it has given one boil, it is to be immediately stopped with a little cold water. A fresh quantity of sulphate of iron, to the amount of two pounds, is then added, and the stuff is kept in it for another hour, after which it is taken out, washed and aired; it is again put into the copper, and constantly stirred for an hour. It is then carried to the river, well washed, and fulled. To soften the black color, and make it more firm, another liquor is prepared with weld. This is made to boil for a moment, and when it is cooled the stuff is passed through it. By this process, which is indeed somewhat complicated, a beautiful black color is produced.

122. But the methods usually followed for dyeing black, are more simple. Cloth, which has been previously dyed blue, is merely boiled in a vat of galls for two hours. It is then kept two hours, but without boiling, in the vat of logwood and sulphate of iron, and afterwards washed and fulled. According to Hellot's process, a liquor is to be prepared of a pound and a half of yellow wood, five pounds of logwood, and ten pounds of sumach, for every fifteen yards of deep blue cloth; and, the cloth having boiled in this for three hours, ten pounds of sulphate of iron are added; the cloth is allowed to remain for two hours longer, when it is taken out and aired, after which it is again returned to the vat for an hour, and then washed and fulled.

When stuffs are to be dyed at less expense, instead of the blue ground, a brown or root-colored ground may be substituted. This brown or fawn color is communicated by means of the root of the walnut-tree, or green walnut-peels. The stuffs are then to be dyed black, according to some of the methods already described.

123. The proportions of the ingredients employed by the English dyers are, for every hundred pounds of cloth previously dyed a deep blue, about five pounds of sulphate of iron, five pounds of galls, and thirty of logwood. The first step in the process is to gall the cloth, after which it is passed through the decoction of logwood, to which the sulphate of iron has been added.

124. As a substitute for galls, the leaves of the arbutus, uva ursi, have been recommended, and employed. The leaves must be carefully dried, so that the green color may be preserved: 100 pounds of wool are boiled with sixteen pounds of sulphate of iron, and eight of tartar, for two hours; the following day the cloth is to be rinsed as after aluming; 150 pounds of the

leaves are then to be boiled for two hours in water, and after being taken out, a small quantity of madder is to be added to the liquor, putting in the cloth at the same time, which is to remain about an hour and a half. It is then taken out and rinsed in water. By this process, it is said, that blue cloth receives a tolerably good black, but white cloth becomes only of a deep brown.

125. After the operations for dyeing the cloth have been finished, it is washed in a river, and fulled, till the water runs off colorless. Soap suds are recommended by some in fulling fine cloths, but it is rather difficult to free the cloth entirely from the soap. After the cloth has come from the fulling mill, some propose to give it a dip in a bath of weld, by which it is said to be softened, and the color better fixed; but, according to Lewis, this operation, which in other cases is of advantage, is useless after the cloth has been treated with the soap suds.

126. Of Dyeing Silk Black.-In communicating a black color to silk, different operations are necessary, such as boiling, galling, repairing the vat, dyeing, and softening. To give a deeper shade to silk, it is necessary to deprive it of the gummy substance of which we have already spoken. This is done by boiling it four or five hours with one-fifth of its weight of white soap, and afterwards beetling and carefully washing it. The gummy substance, before mentioned, which silk in its natural state contains, does not increase the strength of the silk, which is then called raw; but renders it more liable to wear out, from the stiffness it imparts to it: and though raw silk takes a black color with more facility, than silk which has been scoured or divested of its gum, that black is much less perfect, and resists the re-actives calculated to dissolve the coloring matter, in a much less forcible manner.

127. In the process of galling silk, threefourths of its weight of galls are to be boiled for three or four hours, but the proportion must depend on their quality. After the boiling, the liquor is allowed to remain at rest for two hours; the silk is then put into the bath, and left there from twelve to thirty-six hours, when it is to be taken out, and washed in the river. But as silk is capable of combining with a great proportion of the astringent principle, or tan, from which it receives a considerable increase of weight, it is allowed to remain for a longer or shorter time, as the silk is required to have more or less additional weight. Hence to communicate to silk, what is called a heavy black, it is allowed to remain longer in the gall-liquor; the process is repeated oftener, and the silk is dipped in the dye a greater number of times

128. While silk is preparing for the process of dyeing, the vat is to be heated, and should be occasionally stirred, that the grounds which fall to the bottom may not acquire too much heat. It should always be kept under the boiling temperature. Gum and solution of iron are added in different proportions, according to the different processes. When the gum is dissolved, and the liquor near the boiling temperature, it is left to settle for about an hour. The silk, which in general is previously divided into three parts,

that each may be successively put into the vat, is now immersed in it. Each part is then to be three times wrung, and, after each wringing, hung up to air. The silk, being thus exposed to the action of the air, acquires a deeper shade. This operation being finished, the bath is again heated, with the addition of gum and sulphate of iron, and this is repeated two or three times, according as the black required is light or heavy. When the process is finished, the silk is rinsed in a vessel with some cold water, by turning or shaking it over.

129. Silk, after it has been taken out of the dye, is extremely harsh, to remove which it is subjected to the operation of softening. A solution of four or five pounds of soap for every 100 pounds of silk, is poured through a cloth into a vessel of water. The solution being completed, the silk is immersed, and allowed to remain in it for about fifteen minutes; it is then to be wrung out and dried.

130. When raw silk is to be dyed, that which has a natural yellow color is preferred. The galling operation must be performed in the cold, if it be desired to preserve the whole of the gum, and the elasticity which it gives to the silk; but if part only of it is wished to be preserved, the galling is to be performed in the warm vat.

131. The dyeing is also performed in the cold. All that is necessary is to add the sulphate of iron to the water in which the stuff is rinsed. By this simple process, the black dye is communicated. It is then washed, beetled once or twice, and dried without wringing, that its elasticity may not be destroyed. Raw silk may be dyed by a more speedy process. After galling, it may be turned or shaken over in the cold bath; and thus by alternately dipping and airing the stuff, the operation may be completed. It is then to be washed and dried as before.

132. The method of dyeing velvet at Genoa, which has been simplified and improved in France, is thus described by Macquer. For every 100 pounds of silk, twenty pounds of Aleppo galls, reduced to powder, are boiled in a sufficient quantity of water for an hour. The bath is allowed to settle till the galls have fallen to the bottom; they are then taken out, and two pounds and a half of sulphuric acid, twelve pounds of iron filings, and twenty pounds of gum, are put into a copper, pierced with holes in all directions. This vessel is suspended by means of two rods passed through its handles, in the boiler, but so as not to touch the bottom. The gum is left for an hour to dissolve, but must be stirred occasionally. If after this time the gum has not all left the pierced copper, it is a proof that the liquor is saturated with it; but if, on the contrary, the whole has disappeared, from two to four pounds more may be added. This cullender should remain constantly suspended in the boiler, except when the dyeing is going on, during which time it must be removed. During these operations the boiler must be kept hot, but not allowed to boil. The galling of the silk is performed with one-third of its weight of Aleppo galls. The silk is allowed to remain in the liquor for six hours the

first time; then for twelve; and for the rest, secundum artem.

133. Dr. Lewis remarks, that though white silk may be dyed a good black, without using either logwood or verdigris, the addition of those two ingredients contributes greatly to improve the color both in silk and in wool. But as the great use of galls in dyeing silk black renders it very expensive, it is of consequence to find some method of diminishing their quantity. M. Anglês proposes the following process :-When the silk has been carefully boiled and washed in the river, it is to be immersed in a strong decoction of green walnut-peels, and left in it till the color of the bath is exhausted. It is then taken out, slightly wrung, dried, and washed in the river. The decoction of walnut-peels is made by boiling a full quarter of an hour, when it is taken from the fire, and suffered to subside before dipping the silk, which has been previously immersed in warm water. A blue ground is next given by means of logwood and verdigris. For every pound of silk, an ounce of verdigris is dissolved in cold water: the silk is left in this solution two hours; it is then dipped in a strong decoction of logwood, wrung out slightly, and dried before it is washed at the river. For light blacks, galling may be altogether omitted; but for a heavy black, half a pound of galls must be employed for every pound of silk intended to be dyed. To prepare the liquor, two pounds of galls and three of sumach are macerated in twentyfive gallons of water over a slow fire, for twelve hours. After straining, three pounds of sulphate of iron, and as much gum arabic are dissolved in it. In this solution the silk is dipped at two different times, leaving it in two hours each time, taking care to air it after the first dipping, and to dry it before giving the second fire, when it is to be again aired and dried it is then beetled twice at the river; after which a third fire is given it, in the same manner as before, except that it is left in the liquor four or five hours. When drained and dried, it is again beetled twice at the river. The heat during the operation must not exceed 120° of Fahrenheit's thermometer; and before the last two fires, an addition of half a pound of sulphate of iron and as much gum arabic is to be made.

For removing the harshness that silk acquires from the black dye, M. Anglês proposes that a decoction of weld should be preferred to a solution of soap; and observes that if silk be dyed blue with indigo, previous to its being dipped for black, it will take only a mealy black, but that a velvety black will be obtained, if it be prepared with logwood and verdigris; and that green walnut-peels soften the silk.

134. Of Dyeing Cotton and Linen Black.To impart to cotton and linen a deep black dye that will resist the action of soap, is attended with considerable difficulty. Several methods have been proposed as improvements on the old process; the following, practised at Rouen, is thus described by M. d'Apligny. The stuffs are first dyed sky-blue in the usual manner, and are then wrung out and dried. After this they are galled for about twenty-four hours, allowing four ounces