The Dyer's Guide / Being a compendium of the art of dyeing linen, cotton, silk, wool, muslin, dresses, furniture, &c. &c.; with the method of scouring wool, bleaching cotton, &c., and directions for ungumming silk, and for whitening and sulphuring silk and wool; and also an introductory epitome of the leading facts in chemistry, as connected with the art of dyeing

The Calico-Printers' mordant or base of alum for yellow and red goods, either for printing or dyeing; and on compound colours.

Take one gallon of soft and pure water, of a heat of 150°, three pounds of common alum, one pound and a half of sugar (acetate) of lead; mix these together, and let them stand for two or three days, so that they may incorporate, often stirring them during that interval; then add two ounces of pearl-ash, and the same quantity of clean powdered chalk or whiting. After a time the clear liquor, now become an acetate of alum, must be drawn off. When used, it is thickened either with paste, flour, or gum arabic, or senegal; four pounds of either of the gums to each gallon of liquor[5]. A block or a press similar to a copper-plate press for paper, but much larger, and having the copper plates in proportion, is employed to spread the acetate of alum from a utensil called a sieve, which is, however, not porous, while a boy or girl called a Teerer, works it smooth; when smooth on the sieve, the printer applies his block, and charges it with the acetate of alum; the block thus charged, is correctly put on the cotton cloth, which is laid upon a blanket spread upon a table; it is then struck with a mallet once or twice, by which, or by the pressure of the rolling-press, if copper-plate, the acetate of alum is driven into the pores of the cloth. The cloth thus prepared, is hung up in a hot stove, and dried by a high degree of heat. The goods are now ready, if for red, for the madder; and if for yellow, for the weld copper. Sometimes, however, lately, the colour is previously prepared, and applied at once in more instances than are prudent. To the above mordant, M'Kernan adds three ounces of sulphate of copper, omitting the potash; and he adds, "When the colour is wanting on the scarlet cast, omit the sulphate of copper."

Wool readily takes the alum at a boiling heat; common alum is in many instances proper for wool; and in others, where it might be improper, it is corrected by the use of argol or cream of tartar.

Yellow and red produce orange; red and blue, purple; but upon cotton, a scarlet, purple, or crimson cannot be produced in any way equal to those colours in wool or silk. Yellow and blue form the green.

On Bleaching Linen, Cotton, &c.

We cannot enter with much minuteness into this part of the subject, more especially as the art of bleaching is usually a separate one from that of dyeing. Yet as in fact the arts of dyeing and of bleaching depend in a great degree on the same principles, some notice of bleaching, in a treatise on dyeing, seems absolutely necessary.

Linen, cotton, and other cloths, were for ages deprived of their colour, in other words, bleached, rendered white, by a tedious process. Thus, the article to be bleached being boiled in a solution of pot-ash, was washed, and then spread on the grass in a field, watered occasionally, and, thus exposed to the atmosphere for two or three months, became white. This method is, however, in part, if not now entirely, dispensed with. M. Berthollet, an ingenious French chemist, to whose valuable work on dyeing we have before alluded, employed what was then called oxygenated muriatic acid, now chlorine, to perform in a few days what before took months to accomplish. His method was as follows. To six pints of powdered oxide of manganese he added sixteen of muriate of soda, (common salt) and twelve of concentrated sulphuric acid diluted with an equal quantity of water. These were placed in a leaden retort and distilled: the product was oxygenated muriatic acid, or chlorine, which being conducted to a vessel containing the material to be dyed, produced the same effects as the former tedious process, and bleached as much, in two or three days, as was before done in two or three months. This process has been since much further improved by the use of a combination of chlorine with lime, called chloride, or oxymuriate of lime. This article is at present used in almost all the bleaching grounds in the United Kingdom. It appears, therefore, that upon the use of the agent, chlorine, does the expedition and whiteness of modern bleaching principally depend. Yet it ought, nevertheless, to be stated, that although, in the hands of scientific and judicious persons, chlorine is one of the most powerful agents in bleaching that ever was discovered, still, in the hands of bungling and avaricious persons, it may contribute greatly to the destruction of the cloth; and therefore, even now, a demand is occasionally heard for the old method of bleaching.

These processes constitute the art of the bleacher; the dyer has seldom any thing to do with them except in piece-goods or rough cambric, which he has sometimes to dye black as they come from the bleacher's in a state which they call once boucked; and sometimes he has them just as they come from the weaver; in which case, if for black, they need not be bleached white, but should be boiled in pot-ash, to take out the grease, &c.

On the theory relative to fast and fugitive colours.

Many attempts have been made by chemical philosophers to account for the permanence or want of permanence of various colours, when imparted to cloths and other bodies as a dye. Among these, Hellot, D'Apligny, and others of the old, and Berthollet, Bancroft, Henry, and others of the modern school, may be mentioned.

The power of resisting vegetable acids, alkalies, and soap, and, above all, the action of air and light, constitutes the durability of a colour. But this property has a very unequal standard, according to the nature of the colour and the species of the stuff.

There is no obscurity in the action of water, alkalies, acids, and soap: for a solution is effected by means of these agents, or a small portion of acid or alkali unites to the combination, which forms the colour. But this is not the case with the action of light and air. Till lately, however, it was not known in what this action consisted.

Of the two principles which compose atmospheric air, it is only the oxygen gas which acts on the colouring particles. It combines with them, and thus impairs their colour or makes them fade. But its action is soon chiefly exerted on the hydrogen which enters into their composition, and it thereby forms water. This effect may be compared to a feeble combustion. Hence the carbon, which enters into the composition of the colouring particles, becomes predominant, and the colour usually passes to yellow, dun, or brown, or other appearances.

Light promotes this decomposition of the colouring particles, which frequently takes place only with its concurrence, and thus it contributes to the destruction of the colour. Heat also favours the same result, but less efficaciously so, unless it have a certain intensity.

It is concluded, therefore, that colours are more or less fixed in the air, according to the greater or less tendency which the colouring particles have to undergo this change[6]. Hence the utility of mordants in rendering fugitive colours fast.

To prove the colours of Dyed Stuffs, &c.

The natural proofs of a dye's being effectual, are exposure to the air, to the sun, or to rain. If the colour be not changed by such exposure after twelve or fourteen days, it may be considered as fixed. These proofs are not, however, adapted to every colour: for some resist the action of air, light, and rain, yet are nevertheless injured by certain acids. There are also colours which do not resist the natural proofs and yet remain unchanged by acids.

Colours may be arranged in this respect in three classes: the first class is tried with alum, the second with soap, the third with tartar. For the proof with alum, half an ounce of this salt must be dissolved in a pint of water in an earthen pipkin, and into this liquor is to be put half a quarter of an ounce of the dyed thread or stuff, the whole being boiled about five minutes; it is then to be washed clean with water. Thus are tried crimson, scarlet, flesh-colour, violet, ponceau, peach-blossom, different shades of blue, and other colours bordering on these.

The next proof consists in boiling a quarter of an ounce of soap in a pint of water, with half a quarter of an ounce of the dyed stuff or thread for five minutes. With this proof all sorts of yellow, green, madder-red, cinnamon, and similar colours are to be tried.

The proof with tartar consists in boiling one ounce of that salt, previously powdered very fine, with a quarter of an ounce of dyed thread or stuff, in a pint of water for five minutes. This proof is used for all colours bordering upon fallow, or hair-brown.—Journal of Science, vol. xxii. 219.

But notwithstanding these general rules may be given for dye-tests, yet so many are the niceties in this art, that, after all, nothing but long practice combined with scientific knowledge, will enable the dyer to become in this respect, a complete and successful artist.

On dye-houses and the water proper for dyeing.

The dye-house should be as spacious as possible, according to the quantity of work intended to be done in it; it should be also as near as possible to a clear running stream. The floor should be a mixture of lime and cement, and sufficiently inclining, so that water, the old contents of the vats, &c. &c. may run off freely when thrown down.

A dyer cannot be too particular in regard to the water which he uses. Some pump, well, and other spring waters, contain iron; this is injurious to many colours, while for black, brown, slates, and grey, it is very advantageous. It has been supposed that some dyers succeed in dyeing even the very same colour in a superior manner, in consequence of the peculiar purity or other properties of the water which they use.

To discover whether water contains iron or not, a little tincture of galls or prussiate of potash must be dropped into it; if a purple or blue tinge be produced in the water, we may be assured that it does contain iron.

For dyeing delicate colours, the water, which ought to be chosen for such purpose the purest and best, should be heated with bran in a bag, when much of the contents of the water inimical to dyeing will rise to the top in the form of a scum, and should be taken off just before the water boils. Instead of bran, a little alum will answer the same purpose when it is not inimical to the colour intended to be dyed.

The boiling point of water is at the degree of 212° of Fahrenheit's thermometer; the freezing point is at 32° of the same instrument; blood heat is at 98°.

Miscellaneous observations.

The limits and price of this manual preclude the possibility of our giving plates to explain some of the machinery and utensils which are now employed in dyeing. To inform a dyer what kind of coppers, casks, and vats are necessary, would seem to be superfluous; and the pupil may soon acquire such knowledge in the dye-house. Should a dyer find it his interest to undertake a branch of his art of which he has not any previous knowledge, he had better engage a man who understands it; if, however, he thinks himself competent to manage it, but is unacquainted with the best modern utensils appropriated to that particular branch, he had better get a dyer's labourer who has been used to it; a man of sufficient intelligence may be found with due encouragement to perform this part. It may just be added, that Ure's Berthollet and Mr. M'Kernan's work, both contain numerous explanatory plates of the utensils and machinery which are described and recommended in those works.

All solutions and decoctions of Brazil wood, logwood, fustic, &c. should always be prepared in the same quantity and proportion, and one measure be invariably set apart for each. This observation is meant more particularly to apply to drugs in stock, always kept in a state of preparation ready for any process or work which may occur. The drugs just named may be kept in a prepared state; but weld boiled will not keep, nor will some others which are mentioned in the body of the work.

Weld, as it will not keep, should be used thus: a copper in proportion to the size of the work should always be used; and as weld will bear boiling and re-boiling, it can be boiled by the half bundle or more according as it may be wanted, whether you work little or much. If you are exact and near in your estimate, practice will soon render you perfect in any branch. It should be observed too, that to dye to pattern cannot be the result of a receipt, without a great latitude be left for the judgment.

The most difficult part of dyeing is that of light drabs, stone drabs, &c.

Nothing but practice will qualify you for this and all pattern dyeing: the way, and the only good way to obtain practice, is to work with all possible regularity. In the dyeing of fancy cloths in the clothing districts of Yorkshire, Gloucestershire, and other fine cloth manufactories, the manufacturers who dye their own cloths, as well as dyers of the greatest eminence, always number, measure, weigh, and time all the component parts of their various processes of dyeing. Such in fact ought to be the universal practice; and then a person of ordinary abilities may soon be able to perfect his processes and obtain the best results.

Hence, however, it is very necessary that the dyer should have a competent knowledge of chemistry and drugs, that he may be able to judge of the goodness of the articles which he uses, and of the numerous and extraordinary combinations into which they enter. To chemistry, in particular, every able and scientific dyer must be largely indebted; for this reason it is that we have endeavoured, in this introductory chapter, to sketch some of the most important facts in this universal and interesting science.

In possession of these qualifications, and working upon the above plan, the dyer can never be far from the desired result in all his processes. His deviations, if any, will be few, as from his knowledge, he will soon perceive the first approach of any incorrectness, and be able to adjust it generally without much inconvenience.

The chemical terms now introduced into treatises on dyeing are chiefly taken from the Greek language, and are used in such a manner as to convey, by their etymology, an idea of the nature of the substances to which they are applied. Oxygen implies the producer of acid: hydrogen, the producer of water; nitrogen, the producer of nitre, &c. The term gas has been explained above. Caloric is a term used by chemists for heat; but caloric is used in a more extensive signification than the term heat, thus: although a gas might possess no sensible heat, yet being in a gaseous state, it is assumed to contain a certain portion of caloric which keeps it in its gaseous state; the same observation will apply to liquids whether aqueous, oleous, or metallic.

All the measures mentioned in this work unless otherwise described, are those usually called in this country WINE MEASURE, and not those which have been introduced by a late act of parliament, called IMPERIAL MEASURES.

CHAPTER II.
ON DYEING COTTON.

To dye cotton a Saxon or chemic blue—Sulphate of indigo—Saxon or chemic green—To set a cold indigo vat—Another indigo vat—To dye cotton a fast green with the cold indigo vat and weld—Another cold blue vat for linen and cotton—Solution of indigo for penciling printed muslin, &c.—To dye cotton a fast buff—To dye cotton pink.

We refer the reader to the preceding chapter for many observations relative to cotton, with which, in order to understand correctly the best method of dyeing this material, it is necessary that he should become acquainted: indeed, the whole of that chapter ought to be well studied by every one desirous of becoming an expert dyer.

To dye cotton of a Saxon or chemic blue.

This is performed with the sulphate of indigo thus:—put into a brown stone glazed earthen pot four pounds of good sulphuric acid, add to it twelve ounces of good indigo finely powdered, stirring the mixture very quickly and frequently: break the lumps, if it should get lumpy before it is thoroughly mixed, with a glass rod, or with a stick, the bark of which has been taken off: if for wool or silk, the solution will be fit for use in forty-eight hours, but if for cotton it will not be fit for use till the acid is neutralized by an alkali. Some persons, however, use whiting, but this precipitates and wastes the indigo; others use magnesia, but this is expensive: some, again, use pure or caustic potash prepared thus—take American pot or pearl-ash about seven pounds, put some of it into a brown stone glazed jar, or rather an open pan; upon the ashes put some quicklime recently burnt, and then alternately ashes and lime, slacking the lime with water as it is put on the ashes; let the whole stand together for about two hours: provide now another brown stone earthen vessel with a hole in the bottom, of larger dimensions than the other, put into this a piece of coarse linen to prevent the lime, the impurities, or any foreign body from running through the hole, then upon the bottom put some of the previously mixed lime and ashes, well incorporated, and placed gently upon the linen so as to be sure of its keeping its place and letting the liquor pass through clear. As the mixture is put in add some water occasionally, so as to keep it just covered, and leave room at the top for the swelling of the materials, as the lime especially will increase in bulk. Water must fill the whole, and cover the lime, &c. which will be known by the bubbles ceasing to rise. When it has stood twelve or fourteen hours, water being occasionally added as it is absorbed, some may be drawn out.

To determine whether the carbonic acid has entirely quitted the potash, (and for which purpose the quicklime, having a greater affinity with the carbonic acid than potash has, is specifically applied,) take some of the fluid in a wine glass and drop a drop of sulphuric acid into it; if the carbonic acid has entirely combined with the lime, the sulphuric acid will enter the fluid in the glass quietly, and without any other appearance than so much water; if you still doubt add more drops of the sulphuric acid successively. If the carbonic acid has not entirely left the potash when the sulphuric acid is dropped into the liquor, an effervescence or fermentation will be seen in it. Whenever this is the case the liquor must be returned to the mixture for a longer time, and, if necessary, more lime be added.

When the liquor or ley is fit for use, all of it is to be drawn off, and more water may be added and remain on the ingredients till it is wanted. It is best to keep it close from the air, because as the air contains a certain portion of carbonic acid, the liquor would in time absorb it, and the ley, instead of containing caustic potash, would become a solution of carbonate of potash, and consequently not answer the end designed.

To know when the alkali of the mixture is exhausted, take a piece of paper stained with the juice of the blue flowers of violets, or the blossom of the mallow, which is thus prepared—pound the blossoms in a glass mortar with a glass pestle, and squeeze the juice into a tea-cup, then, with a small hair pencil, cover a sheet of white paper with the juice, and dry it for use. All acids will turn it red, and all alkalies will turn it green; and, therefore, as long as any of the alkali remains in the liquor, the paper thus prepared will, when immersed in it, be stained green.

The comparative strength of such solutions may also be ascertained thus: take a wine-glass full of the liquor, drop into it a few drops of sulphuric acid, stirring it with a glass rod or clean bit of tobacco-pipe, and then apply a bit of test paper; if it appear green more acid must be added and stirred again; apply the test paper a second time, if it be still stained green, a few drops more of the acid must be added, and thus continue till the colour of the paper is neither altered to green nor red: the liquor will then be neither acid nor alkaline, but contain a neutral salt consisting of a combination of the acid and the alkali. By adding, however, a few more drops of the acid, this last will be found predominant, and the test paper, being immersed in the liquor, will be stained red.

By treating different leys in this manner, and counting the number of drops necessary to neutralize each, the strongest ley will always be found that which requires the greatest quantity of acid for the purpose.

Alkaline leys are also to be judged of by their weight compared with that of water; a wine pint of water usually weighs about sixteen ounces avoirdupoise; all alkaline leys are heavier than water, and the heavier they are the more alkali they necessarily contain. A wine pint of some of them will weigh more than seventeen ounces.

To return to the dyeing of cotton a chemic blue: (to which a knowledge of these chemical processes, as well as of other processes in our work, is essentially necessary,) take some of the blue liquid prepared with indigo and sulphuric acid, as before directed, and put it into a vessel large enough to hold two or three times as much as is intended to be put in, in order that there may be room to stir it; add some of the potash, or alkaline liquor, by degrees till, after several trials, the mixture ceases to be sour; or, if you do not like to taste it, take a small slip of cotton or muslin and dip it in, after having wetted it out in warm water. If the acid be neutralized the cotton will be sound, if not it will be tender when dried: if the acid predominates much the cotton will be as rotten as tinder; when the cotton is perfectly strong and sound after being dried, the liquid is in a proper state to dye both cotton and muslin.

The goods to be dyed must first be wetted out and wrung, then work them in the flat tub with water, with a little of this blue added, and well stirred in proportion to the shade wanted. From half a pint to a pint of the liquid blue is sufficient for two pieces of twenty-four or twenty-eight yards each, if not of a very full pattern.

Blue, when dyed, should be dried in a cool stove, and if book-muslins, framed; furniture should be stiffened, glazed, or calendered.

The preceding are essentially the same directions for preparing and dyeing with the chemic blue which were given in the first edition of this work, and which we see no reason to alter. As, however, for silk in particular, another method has been given in the late work of Mr. M'Kernan, we give his processes below.

Sulphate of Indigo.

"Take one pound of the best flora indigo in very fine powder, put this into a stone-ware or lead vessel, then add gradually three pounds of the best sulphuric acid, specific gravity 1.800; mix well and stir often, and in twenty-four hours the indigo will be dissolved. Adding three ounces of sulphur to the acid, and heating it to 180°; then, when cooled to 100°, pouring the acid off the sediment, and then adding to it the indigo, is considered the best way of opening or dissolving the indigo. When the indigo and acid have been mixed twenty-four hours, add three pints of boiling water; stir often; when cold it will be fit for use."

To neutralize the sulphate of indigo.

"Take six pounds of alum and dissolve it in two gallons of water at 120°, when dissolved add, by degrees, five pounds of pearl-ashes until the acid of the alum is neutralized and the alumine formed, then put the whole on a piece of calico that has been hooked in a square frame, or tied over a vessel; when the liquor has run off then add one gallon of boiling water on the alumine and stir it up well. When the water has gone through the calico; the alumine is fit for use. Then add a part of this alumine to some of the sulphate of indigo until the acid is neutralized."

Saxon or chemic GREEN.

The same blue vat will do for green; but it is best to make another by putting only eight ounces of indigo instead of twelve to four pounds of sulphuric acid. If the preparation has been made two or three months it is the better, having been often stirred before it was neutralized with the alkali.

Prepare a strong decoction[7] of old fustic, which should always be ready at hand as a store, keeping plenty according to the work to be done, including cotton, silk, and worsted goods.

Mix some of the chemic blue with the decoction of fustic in the following manner: put into a tub six pails of soft clear water, to which add a pint of the neutralized blue; and six pails of the decoction of fustic; stir all well together. Some dyers add a little weak alum liquor till it just tastes before they put in the blue; it should be but little, otherwise it will precipitate the fustic. This mixture should stand two hours to settle.

The muslin or calico, say two pieces of twenty-four yards each, should, with the usual precautions, be passed through a strong decoction of old fustic or turmeric as hot as the hand will bear. They are then to be taken out and submitted to a quantity of the green mixture above, described, in proportion to the fulness of the green required. When finished, whether for the calenderer or glazer, they should be dried in a moderately warm stove.

These two colours are very fugitive, especially upon cotton goods; but sometimes the customer will not go to the price of the fast green or blue, hereafter to be described.

To set a cold indigo vat for cotton, &c.

Put three pounds of slacked lime, sifted, into six quarts or more of boiling water; stir the mixture well for some time, and after it has settled, draw off the clear liquid, to which add three pounds of sulphate of iron, stirring it well till all is dissolved; let it settle till the next day; have ready a deal cask, because one made of oak would blacken and otherwise injure the dye, in consequence of the affinity between the tannin, &c. of the oak and the sulphuric acid. Put into the cask seventy-five gallons of water, to which add the mixture of lime and sulphate of iron; take now three pounds of indigo, well ground and ready at hand, dissolved in three pints of strong solution of potash, such as was directed to be prepared for neutralizing the chemic blue. Put this solution of indigo and potash into the tub with the water, lime, &c.; after it is well stirred, and left to settle, it produces a deal of froth; but the liquor takes a fine green colour, which turns to blue when exposed to the air.

Soda may be used instead of potash, if treated the same way. Soda, it may be observed, forms the usual ley of the soap manufacturer; and answers for soap much better than potash, because its combinations do not usually absorb moisture from the air: potash, and several of its combinations, do so.

Another indigo vat.

Take five hundred quarts of water; indigo seven or right pounds. The boiler must be iron.

Boil the indigo with sixteen pounds of a liquor made with potash and eight pounds of lime. After the lime and potash have been in contact, as in all these instances they should be, from twelve to twenty-four hours, to take away the carbonic acid from the potash, the clear liquor of this mixture is what must be used. The indigo must be previously powdered, and ground extremely fine in water before it is put into the alkaline liquor. The mixture must now be added to the five hundred quarts of water, and the whole boiled till the indigo rises to the surface like cream, and till, in striking the bottom of the boiler with a stick, it is found to contain no solid substance.

While the indigo is boiling, another eight pounds of lime must be slacked in about twenty quarts of warm water; dissolve in this lime-water sixteen pounds of sulphate of iron. The vat being half filled with water, the solution of lime and sulphate of iron is to be put into it; the indigo solution is now also to be added. The vat, being thus filled to within about three or four inches of the edge, must be stirred two or three times a day till it is fit for dyeing, which it will be in about forty-eight hours, and sometimes sooner, according to the temperature of the air, by which the completion of the process is more or less accelerated.

When the strength of the vat is exhausted, it must be, of course, replenished. If the liquor becomes black, it wants sulphate of iron; if yellow, lime is required. When the indigo is far spent, more must be added in the same manner as at first.

In this vat, as respects the blue dye, if it be for muslin, calico, &c., the form should be square, about two yards long, one yard to one and a half wide, and from seven to eight feet deep; the pieces of cloth are to be hooked into a frame.

Where much work is done, it will be necessary to have two or three such vats, in order that they may be worked in succession: by stirring them some hours previously to working, the weaker will do for the lighter shades, the stronger for the fuller colours. If the vat is in proper order, the goods always come out green, and turn blue in the air. This should be ascertained by small patterns previously to working the whole. When any goods are dyed in these vats, if not full enough at one dip, they may be left a certain time, and then be dipped again, once or more, as they appear to require it.

When they are blue enough, and fully aired, they must be taken from the hooks, and well washed off in two or three fresh clean waters, or at a wash wheel in a clear running stream. When perfectly clean, they are ready for the calenderer or glazer.

To dye cotton a FAST GREEN, with the cold indigo vat and weld.

After dyeing muslin blue in the blue vat, weld must be boiled in the same manner as for fast yellow. The quantity of weld to be used, must be according to the fulness of the blue ground, and of what shade the green is to be; a proportion of alum must also be used. The goods, after being worked in the same manner by the selvage, must be washed off, and stiffened, if for the glazer, but not if for dress, but be framed by the muslin dresser.

Another cold BLUE vat for linen and cotton.

The indigo is to be powdered, and put into warm water with sulphate of iron, in quantity twice the weight of the indigo, to which is also to be added, the same weight of fresh-burnt lime. The water should be only sufficient to mix it thick at first; keep it stirred; and, as it becomes dissolved and green under the surface, increase the water, often stirring and trying the mixture, by putting in a pattern between the stirrings, at some hours distance, between each pattern, and increasing the water: in twenty-four hours it will be fit for use.

Solution of indigo for penciling printed muslin, &c.

To twenty-five gallons of water, add sixteen pounds of indigo, and thirty pounds of carbonate of potash; when mixed, and placed over the fire, as soon as the mixture begins to boil, add quicklime, by a little at a time, to render the alkali caustic; then twelve pounds of red orpiment, and boil till it will give a yellow colour to transparent glass.

This form is from Haussman. Were the author to make this solution of indigo, he would first make the alkali caustic with lime, and then put the clear liquor to the other materials.

Mr. M'Kernan gives another form for pencil blue with indigo: the principal differences between which and the above, consist in adding equal parts of brown sugar and gum senegal to it, which, in regard to the addition of the gum, is, we presume, a great improvement.

Dr. Ure (Notes to Berthollet, vol. ii. page 437.) gives a similar form from Vitalis, for topical or pencil blue; but he adds, it was much used formerly. Another blue, of less permanence but more brilliance, is now preferred; it is made thus:—

Into an earthen pot four ounces of finely ground and sifted Prussian blue are to be put. Over this must be slowly poured, stirring all the while, sufficient muriatic acid to bring it to the consistence of syrup. The mixture is to be stirred every hour for a day, and afterwards thickened with from four to eight pots (of two litres each; a litre French contains about two wine pints;) of gum-water, according to the shade wanted.

To dye cotton a FAST BUFF.

Take a brown stone pan or pipkin, glazed. It must not be the common glazed wares, because these are glazed with lead, and the acids will dissolve the lead; if, therefore, such are used, the lead being dissolved, will be mixed with the dyeing materials, and sometimes totally spoil the dye. Stone-ware, if used with care, will bear the fire: such ware is usually glazed with muriate of soda or common salt.

Having a proper vessel capable of holding from two quarts to a gallon, fill it half-full of strong nitric acid, to which add, in small quantities at a time, either old horse-shoe nails from the farrier, they being the purest iron, or the cuttings of tin-plate from the tin-man's, for this is also very pure iron, although covered with tin; but the small portion of tin in the iron is not inimical to the dye. Be careful not to put too much in at a time, nor to stoop near to it while the solution is going on, as the red fumes arising are very noxious; and if the iron be added in large quantity, so much effervescence would be produced, that a considerable part of the liquor would be thrown over the top of the vessel.

When this solution is prepared in haste the air is greatly contaminated, and therefore it is best to prepare it long before it is wanted, and slowly, by dropping hourly small quantities of the iron into the acid, and then little if any perceptible fumes will arise. Continue this process till, by stirring with a glass rod or tobacco-pipe, you find the iron dissolves more slowly: by keeping a little iron at the bottom, and occasionally adding the acid, you may always have this preparation at hand.

It is to be used thus:—having a copper of hot water ready, put a part of it to some cold in a flat tub till the mixture is as hot as the hand will bear; then, according to the paleness or fulness of your pattern, add some of the solution of iron, and mix it well by stirring: begin with about half a pint for two pieces of twenty-four yards each: it is best to add a smaller quantity than is necessary first, as you can make another addition as you please, but, if you add the solution in excess, to diminish it is by no means so easy. Now, having ready a flat tub with water of as hot a temperature as the hand will bear, put into it a clear solution of pearl-ash, and have also ready another tub of clear cold water to wash off in; then pass the pieces (always taking care to have them well wetted out in one of the tubs of hot water before either the solution of iron or pearl-ash is put into either of them) through the solution of iron six or seven times, edging them over by the selvage to keep them even; next, folding them first even upon a board, wring them out, wash them off and pass them through the solution of pearl-ash; lastly, wash them off again in fresh and clean water: a permanent and bright buff will be found, and as good a colour as can be dyed upon cotton.

We here see what an affinity iron and cotton have for each other when the iron is combined with an acid and the combination in a liquid state. Although the colour is not so beautiful in every instance, yet, be the acid which dissolves the iron what it may, cotton imbibes the iron from it.

What is left of the solutions of iron and the pearl-ash may each be kept in a separate deal tub for use.

To dye cotton PINK.

Take safflower in proportion to its goodness and the quantity of work to be dyed; put it into pure and clear water; tread it in the water till the water becomes fully charged with a kind of extractive yellow colour. It is best to put the safflower into a strong linen bag or sack; a sack containing sixty pounds will take a man two days to wash it clean: if done in a clear running stream the yellow colour will of course run away; if you have a small quantity in a tub it must be let out at a plughole, which every flat tub should have. The safflower must be worked or trod till all the yellow colour is got out of it, or the pink to be obtained from it afterwards will not be bright.

When the safflower is thoroughly washed, take it out of the bag and put it into a deal tub or trough, and add to it pearl-ash in the proportion of six pounds to one hundred pounds of the safflower, which should be weighed before it is wetted. Let the potash be well dissolved in water; pour part of the clear solution off, and mix it thoroughly with the safflower; after having stood for some time strain the liquor through a cloth or sieve into another deal trough. The whole solution of pearl-ash should not be put in at once, but at different times. If there should be reason to believe that the safflower will yield more colouring matter by a farther addition of the solution of pearl-ash, such additional solution may be made. The water for the solution and the solution to the safflower should both be applied cold. Carbonate or mild potash is better than the caustic. By putting the solution of pearl-ash on the safflower at different times it will be readily seen when the fluid passes through the cloth or sieve free from colour.

The colour is of a cherry hue, and is resinous, therefore the water dissolves but little of it; the carbonate of potash is added to dissolve this resin.

To overcome the influence of the pearl-ash, which tinges the red of a yellow colour, some cream of tartar must be finely powdered and dissolved in boiling water, and added to the liquor when it is nearly cold. In the South of France lemon juice is used.

The colour, being thus raised by the cream of tartar, is now to be mixed with cold water in proportion to the fulness of the pattern desired, and the cloth must be worked six or seven times in it, as in other colours.

What is left of the colour must be taken up with some skein cotton, and dried; this may be added to water upon another occasion by saturating the acid with a solution of pearl-ash, which will abstract the dye from the cotton.

The solution of tartar will again redden the colour from the yellow of the pearl-ash; this must be done if any remain, for it will not keep in a fluid state.

We shall not here describe any other process with cotton till we have treated of wool and silk.

For dyeing cotton black, and some other colours, see the chapters V. and VI.

CHAPTER III.
ON DYEING SILK.

To alum silk—The blue vat of indigo for silk—Another blue vat for silk—To dye silk violet, royal purple, &c.—To dye silk lilac—Another process for lilac—Another process for dyeing muslin, &c. lilac—To dye silk a violet or purple with logwood—To dye silk violet with Brazil wood and logwood—To dye silk violet or purple with Brazil wood and archil.

To alum silk.

Forty or fifty pounds of alum being dissolved in a copper of hot water, the solution is to be poured into a tub containing forty or fifty pails of cold water; during the mixing of the solution of alum with the water it should be well stirred lest the cold water should crystallize the alum and spot the silk; when, however, this happens, dipping silk in warm water will dissolve the alum. The silk should be alumed cold, for, if hot, the lustre of the silk will be injured. Alum is used for certain reds and yellows but not for blue. See also chapter VI.

When silk is deprived of its gum so as to acquire the greatest possible degree of whiteness, it is still necessary to have different shades of white, some yellow, some blue, and others reddish; these are known under five denominations, namely, China white, India white, thread or milk white, silver and azure white. All these whites, although differing from each other by very slight shades, are nevertheless apparent, especially when compared with each other, which will be seen in the processes of dyeing silk.

For ungumming and boiling, whitening and sulphuring silk, see chapter VI.

We have described M'Kernan's method of preparing and neutralizing sulphate of indigo in pages 51 and 52, to which the reader will be kind enough to refer: the following blue vat is from Macquer.

The BLUE vat of indigo for silk.

This should be so contrived that heat may be applied to it, which it now mostly is, by steam, as well for woollen woad vats as for indigo vats. For silk, take eight pounds of the finest indigo and six pounds of the best pearl-ash, and from three to four ounces of madder for every pound of ash, besides eight pounds of bran for the whole, washed in several waters to take the flour out. When washed, and the water squeezed out, the bran is to be put at the bottom of the vat; the pearl-ash and the madder being mixed by bruising them roughly together, are now to be boiled a quarter of an hour in a copper containing two-thirds of the vat; the fire being damped, the liquor is then suffered to rest. Two or three days previous to this the indigo is to be steeped in a bucket of warm water, and washed well, the water being changed once or more. Some dyers begin by boiling the indigo in a ley made with one pound of pearl-ash and two buckets of water; they afterwards pound it in a mortar quite wet, and, when it becomes like paste, fill the mortar with the liquor before boiled, and still hot, stirring it for some time. It is then suffered to stand a few moments, and then the clear is poured off into a separate boiler or into the vat. The same quantity of the mixture is then poured upon the indigo remaining in the mortar and mixed as before; again the clear is poured off into the boiler, and the operation is repeated till the whole of the indigo is dissolved in the liquor. The whole of the liquor in the boiler is now to be gradually poured into the vat on the bran at the bottom, adding afterwards the remainder of the composition, grounds and all.

After stirring and raking for some time, the mixture is left to cool till it will bear the hand in it, when a little heat is added to keep it in this state, and so continued till it begins to turn green, which is easily known by trying it with a little silk. When the green begins to appear it should be stirred with the rake, then suffered to stand till the brown and coppery scum which rises upon the surface shews that the vat is come to; or, in other words, the preparation of this part of the process is complete. But as it is necessary to be very certain of this, the scum should be well examined; and if, when blown aside, a fresh scum is immediately formed it is as it ought to be. In this state it is to remain for three or four hours, when a new composition is thus made:—

Put as much water as is requisite to fill the vat into a copper, boiling it with two pounds of pearl-ashes and four ounces of madder as at first. This new liquor is to be poured into the vat, raked and mixed, and being left to stand for four hours it is then ready for dyeing.

When a vat or vats are set for green, double the quantity of madder must be added. (See Chap. VI.)

The size of the vat for the above quantity of indigo, should be about five feet deep, two feet or two feet and a half in diameter at the top, and one foot and a half or two feet in diameter at the bottom: the form of an inverted frustum of a cone; or of a sugar loaf inverted, with the pointed top cut off.

In order to produce different shades of blue, the silk intended for the darkest, should be first dipped in the fresh vat and so on to the lightest; as the vat weakens the silk should be kept in longer, till the vat, being exhausted, serves only for the lightest shades. When it begins not only to be weak but dull, it is then necessary to feed the vat with the following composition:

Take of the decoction of pearl-ash with indigo one pound; of madder, two ounces; and a handful of washed bran; boil them together for a quarter of an hour, either in water or a portion of the same vat if yet sufficiently full to afford it; after this mixture is added, it should be well raked and suffered to rest two or three hours, more or less, before the dyeing is resumed.

For the finest blues, however, a fresh vat is the best; and if only pale blues are required, a vat set on purpose with less indigo will answer better than a strong vat which has been weakened, because though weak it will give more vivid colours.