The Jig Wince or Wince Dye Beck.—This dyeing machine is very largely used, particularly in the dyeing of woollen cloths. It is made by many makers, and varies somewhat in form accordingly. Figures 18 to 21 show three forms by different makers. In any make the jig wince or wince dye beck consists of a large rectangular, or in some cases (p. 054) semi-cylindrical, dye-vat. Probably the best shape would be to have a vat with one straight side at the front, and one curved side at the back.



In some a small guide roller is fitted at the bottom, under which the pieces to be dyed pass. Steam pipes are provided for heating the dye-liquors. The beck should be fitted with a false bottom, made of wood, perforated with holes, or of wooden lattice work, and under which the steam pipes are placed. The object being to prevent the pieces from coming in contact with the steam pipes, and so (p. 055) preventing the production of stains. Above the dye-vat and towards the back is the wince, a revolving skeleton wheel, which draws the pieces out of the dye-vat at the front, and delivers them into it again at the back. The construction of this wince is well shown in the drawings. The wince will take the pieces full breadth, but often they are somewhat folded, and so several pieces, four, five or six, can be dealt with at one time. In this case a guide rail is provided in the front part of the machine. In this rail are pegs which serve to keep the pieces of cloth separate, and so prevent entanglements. The pieces are stitched end to end so as to form an endless band. When running through the vat they fall down in folds at the back part of the beck, and are drawn out from the bottom and up in the front. Each part thus remains for some time in the dye-liquor, during which it necessarily takes up the dye.



Figures 18 and 19 show forms of these wince dyeing machines, constructed of wood, and very largely used in the dyeing of woollen cloths. They are serviceable forms, and give very good results, being suitable for all dyes.

Figure 20 is a form of machine better adapted than the preceding (p. 056) for the dyeing of plush fabrics. In this kind of cloth it is important that the pile should not be interfered with in any way, and experience has shown that the winces of the form shown in figures 18 and 19 are rather apt to spoil the pile; further, of course, plush fabrics are dyed full breadth or open. In the wince now shown all troubles are (p. 057) avoided, and plush fabrics can be satisfactorily dyed in them.



Figure 21 shows a dye-bath built of iron, cased with copper, suitable for dyeing most colours on woollen cloths.



In the jig and wince dyeing machines the pieces necessarily are for a part of the time, longer in the case of the jigger than in that of the wince, out of the dye-liquor and exposed to the air. In the case of some dyes, indigo especially, this is not desirable, and yet it is advisable to run the cloth open for some time in the liquor so as to get thoroughly impregnated with the dye-liquor.

The so-called hawking machine, figure 22, is an illustration of Read Holliday's hawking machine, made by Messrs. Read Holliday & Sons, of Huddersfield. There is the dye-vat as usual; in this is suspended the drawing mechanism, whose construction is well shown in the drawing. This is a pair of rollers driven by suitable gearing, between which the cloth passes, and by which it is drawn through the machine. A small roller ensures the cloth properly leaving the large rollers, (p. 058) then there is a lattice-work arrangement over the pieces are drawn. In actual work the whole of this arrangement is below the surface of the dye-liquor in the vat. The piece to be dyed is threaded through the machine the ends stitched together, then the arrangement is lowered into the dye-vat and set in motion, whereby the cloth is drawn continuously in the open form through the dye-liquor, this being done as long as experience shows to be necessary. This hawking machine will be found useful in dyeing indigo on wool, in mordanting and dyeing wool with the Alizarine series of dyes.



CHAPTER IV. (p. 059)

THE PRINCIPLES AND PRACTICE OF WOOL DYEING.

The various methods which are used in dyeing wool have, of course, underlying them certain principles on which they are based, and on the observance of which much of the success of the process depends. Sometimes these principles are overlooked by dyers, with the result that they do not get good results from their work. It must be obvious to any person with any technical knowledge that all processes of dyeing either wool or silk, or cotton or any other fibre, must take into consideration the properties of the fibre on the one hand, and that of the dye-stuff on the other. Wool must be treated differently from cotton, a process of dyeing which gives good results with the latter fibre would lead to nothing but disastrous effects with wool or silk; on the other hand, processes are used in the dyeing of wool which could not be possibly used for cotton on account of the very different properties of the fibre.

A few words as to the properties of wool as far as they relate to the methods of dyeing may be of use. Wool has the property of resisting the action of acids in a great degree, so that it may be treated with even strong acids with impunity. On the other hand, alkalies and alkaline solutions have strong action on it; the caustic alkalies rapidly dissolve wool, and their use must be avoided in all cases of dyeing this fibre. The carbonates of the alkalies have not so strong an action, and therefore may be used in moderation; nevertheless, (p. 060) too strong solutions of these should not be used. Soap has no disintegrating action on wool, and soap solutions may be used whenever necessary for cleansing or dyeing wool. Ammonia has no action on wool, and it may be used in place of soap if desired. There is one feature of wool that must be alluded to here, and that is its felting property. When wool is boiled with water and is handled a good deal, the fibres clot or felt together into a firm coherent mass. This should be avoided as much as possible, and when wool is cleansed and dyed in the loose condition it is absolutely necessary that every care be taken to avoid felting. This condition is much influenced by the temperature and the condition of the bath in which the wool is being treated, too high a temperature or too prolonged a treatment tends to increase the felting, therefore in dyeing wool prolonged treatment at the boil must be avoided.

Further, the condition of the bath has some influence on this point; it is found that an alkaline bath tends to considerably increase the felting properties of the wool, and on this account dyers invariably avoid the use of both the caustic and carbonated alkalies. Strong soap liquors have also some influence in the direction of increasing the felting, therefore soap should not be used if it can possibly be done without. Ammonia has not so strong a felting action as the other alkalies. Acids, on the other hand, exert a retarding action on the felting of the wool, and this is a matter of some interest and importance in the dyeing of wool, as an acid condition of the bath is necessary for dyeing by far the great majority of colouring matters on this fibre. Alkaline salts, such as Glauber's salt and common salt, exert little or no influence on this felting property, and can be added to dye-baths with impunity, and in many cases with good effect, so far as the quality of dyeing is concerned.

So far as the properties of the wool are concerned, it is seen (p. 061) that an acid condition of the dye-bath will work better than an alkaline condition, and wherever it is possible to use acids such should be added.

What has been said in regard to wool is equally true of all fibres derived from animals in the same way as wool is, such as horse-hair, fur of rabbits, hares and other animals, although, of course, there are some minor differences between different furs in their resistance to the action of acids and alkalies.

The next feature that influences the methods of dyeing wool is the varying properties of the dye-stuffs, or colouring matters. It is obvious that those which, like Magenta or Saffranine, have a strong affinity for the wool fibre must be dyed differently from those which, like Alizarine and Gambine, have no direct affinity for the wool fibre, and, further, which require the aid of mordants before they can be dyed, and on the character of which mordants the colour that is fixed on the fibre depends.

The dye-stuffs, independently of the question whether they be derived from natural sources or be of artificial origin, may be roughly divided into five groups, some of which may also be subdivided again as will be shown later on. These groups may be named the (1) Neutral, (2) Basic, (3) Acid, (4) Mordant, and (5) Indigo dye-stuffs. The first two classes are practically dyed in the same way; but as there is a great difference in the chemical composition of the colouring matters comprised in them, it will be best to consider them separately.

First Method.—This method is used in applying the now large and increasing group of azo dye-stuffs, which are characterised by being able to dye unmordanted cotton from a simple boiling bath. The dye-stuffs that are applied by the method now to be described include such as Benzopurpurine, Chrysamine, Chrysophenine, Titan red, Titan yellow, Benzo brown, Diamine red, Diamine brown, Diamine blue, (p. 062) Congo blue, Congo red, etc. The dyeing is done in a bath at the boil. If the bath contained only the dye-stuffs there would be a liability for the dyeing to be uneven, to prevent which a saline compound, such as salt, is added. Taking it all round, salt is the best body to add as it suits all colours very well indeed. Then come Glauber's salts; borax and phosphate of soda can also be used, but, owing to their slight alkaline properties, they are not so good as the neutral salts, like the two first named. When these colouring matters are dyed on cotton some of them dye best in a bath containing potash or soda, but these bodies, for reasons previously pointed out, are not available in wool dyeing, and should never be used. Wool dyes best in a slightly acid bath, and this may be taken advantage of in dyeing the yellows and blues of this group by adding a small quantity of acetic acid. The reds, as a rule, are affected by acids, and, therefore, it is not possible to use an acid bath with Benzopurpurine, Congo red, with the possible exception of the Titan reds and scarlets, Diamine scarlet, Benzo fast scarlet, Purpuramine, which are faster to acetic acid than the other reds of this class of dye-stuffs.

Probably the best plan of dyeing these colours is to first heat the bath to about 160 deg. F., then enter the goods, and turn over two or three times to ensure that they are thoroughly impregnated with dye-liquor. The bath is now raised to the boil, and, steam being turned off, the goods are handled without further steam until the desired shade is obtained. Another plan is to enter the goods when the bath is at about 150 deg. F., and, after raising to the boil, to work for half to one hour at that heat; but the plan first described gives rather better results, and is far preferable. The dye-baths, as a rule, are not completely exhausted, except when very pale shades are being dyed; in no case is it necessary to throw the dye-bath away, but simply to add the required amount of dye-stuff for a new batch; (p. 063) with those colouring matters which are not entirely exhausted from the bath a smaller amount, generally about three-fourths only, is required to be added, with about one-third the quantity of salt which was added to the first bath. Of course it is not advisable to keep the same bath or liquor in work always, but after about twenty or thirty batches of goods are dyed to throw it away and start a fresh liquor.

As a rule it will be found that these dye-stuffs are more thoroughly taken up from the bath than is the case in dyeing cotton; thus often with the same amount of dye-stuff in proportion to the material used the wool will dye rather a deeper shade than will cotton. In some cases, especially with the blues and violets, the shade is greatly different on wool from what it is on cotton, being generally redder and much stronger. (See the chapter on Union Dyeing.) While the shades are somewhat faster to light on wool than they are on cotton, they are no faster to soaping and in some cases not so fast. What may be the function of the salt, or other such added substance, is not very clear, probably it plays the same part as to similar bodies in dyeing the basic dye-stuffs. The dye-stuffs which are referred to above are all derived from coal-tar, and in the recipes which follow many examples of their use will be found.

There are but few natural dye-stuffs that have any direct affinity for wool. Turmeric, saffron, anotta, are about the only representatives, and these are not of much importance in wool dyeing by themselves, although they are sometimes used in conjunction with other natural dye-stuffs, when they are applied by a process which is adapted more especially for the other dye-stuff which is used.

_Second Method_.—The method of wool dyeing now being dealt with does not differ essentially from that described above, but as it is applied to quite a different class of dye-stuffs it is thought better to consider it as a second method. The dye-stuffs made use of in (p. 064) this method are what are called the basic coal-tar colours, and it may be remarked in passing that there are no natural colouring matters having the same properties. These dye-stuffs are derived from a number of so-called colour bases, such as Rosaniline, Pararosaniline, Methylrosaniline, Phenyl-rosaniline, and Auramine base. Many of these are colourless bodies containing the Amidogen group NH_{2}, which imparts to them basic properties enabling them to combine with solids to form salts, and these salts have a strong colouring power. They form the commercial dye-stuffs Magenta, Saffranine, Thioflavine T, Auramine, Benzoflavine, Brilliant green, Methyl violet, etc., and these are salts (usually the hydrochloride) of colour bases. All these basic dye-stuffs have strong affinity for the wool fibre, and will immediately combine with it, dyeing it in colours which resist washing, etc., to a considerable extent, although there are great differences between the various members of the group in this respect. It has been shown that what takes place in dying wool with these colouring matters is that the colour base combines with the fibre the acid of the dye-stuff remaining in the dye-liquor.

Although it is possible to dye wool with the basic dyes from a plain bath containing water only, yet the results are not satisfactory, especially when working on a large scale; and for dyeing pale shades especially, the affinity of the dye-stuff for the fibre is so great that the first portions of the goods which are entered into the dye-bath have a great tendency to absorb all the dye-stuff, or the larger proportion of it, so that uneven dyeing is the result, one end of the piece of cloth being darker than the other end. This defect is particularly accentuated when pale tints are being dyed, the colouring matter being completely absorbed before all the goods are entered into the bath, but it may be remedied by adding the dye-stuff to the bath in small quantities at intervals during the process of dyeing. The (p. 065) best and most satisfactory method, however, is to add to the bath 10 per cent. of the weight of the wool of Glauber's salt, or some other neutral alkaline salt, which addition almost entirely prevents any defect of uneven dyeing. How these assistant mordants act is somewhat uncertain, the explanation generally given is that they exert a slightly solvent action on the dye-stuff, and so prevent it from going upon the fibre too readily. This is scarcely an adequate explanation, but in want of a better it will have to stand.

The affinity of the basic dyes for wool increases with increase of temperature. This is a property that has an important bearing on the method of dyeing, and to any person who pays some attention to theory in its practical applications it indicates the most rational method of working, which is to enter the goods into the bath cold, or, at the most, at a hand heat, then, after working a short time to get the goods thoroughly impregnated with the dye-stuff, to gradually raise the temperature to the boil and work for from half an hour to an hour longer, even if before this time the dye-bath be exhausted. The reason for giving a fair length of time in the bath is to get the colour properly fixed on the fibre. The combination of the dye-stuff and the fibre is a chemical one, and, as stated above, the dye-stuff has to be decomposed so that the base may combine with the essential constituent of the wool fibre, while it is obvious that this decomposition and then the union of the colour base with the wool must take time, and as it is effected more easily and completely at the boiling point, it is advisable to work the goods in the bath so as to fully insure that they are given the necessary time for the chemical change to take place.

The dye-bath is generally completely exhausted of colour, but if fairly clean it need not be thrown away, but used for another batch of wool by simply adding more Glauber's salt and dye-stuff. After a (p. 066) time the bath gets too dirty to used, when it may be thrown away, and a new dye-liquor made up.

In dyeing for pale shades it is best to add the dye-stuff in small quantities at intervals during the process of dyeing, and to run the goods quickly through the bath, so as not to give the dye-stuff too much opportunity to become absorbed by a portion of the goods only.

Working according to the hints given above, the dyeing of wool with the basic coal-tar colours may be carried out in a very satisfactory manner.

Third Method.—This method consists in dyeing the wool in a bath containing the dye-stuff, a little acid (usually sulphuric) with the addition of Glauber's salt, or some other alkaline salt, the essential feature or principle being that the bath is an acid one. This method is applicable to the large group of azo dye-stuffs derived from coal tar, and also to the acid dyes prepared from the basic coal-tar colours by the process of sulphonation.

It is also used to apply indigo carmine to wool, probably the only good example of a natural dye-stuff applied by this process. Most of the natural colouring matters, such as logwood and fustic, belong to another group of dye-stuffs.

The simple azo dyes are combinations of two or more organic bases, united together by a peculiar and characteristic group of nitrogen atoms. Such azo colours are, however, insoluble in water, and therefore they cannot be used in dyeing and textile colouring, although the firm of Messrs. Read Holliday & Sons years ago patented a process whereby these insoluble azo colours could be developed on the cotton fibre direct, and thus fabrics made from that fibre could be dyed in fast colours. When these insoluble azo colours are treated with sulphuric acid they are converted into sulpho acids, undergoing what is called sulphonation, an operation of the greatest (p. 067) importance and value in the preparation of dye-stuffs. The preparation of indigo extract or indigo carmine from indigo is also a case of sulphonation. The sulpho-acids of the azo colours, of the basic dyes, and of indigo are usually insoluble in water, although there are great differences in their properties in this respect. They will combine with bases such as soda, calcium and potash to form salts which are soluble in water, and it is usually in the form of sodium salts that these azo and acid dye-stuffs are sold to the dyer and calico printer. It is this power of combination with bases that makes them of value in wool dyeing. As Knecht and other authorities have pointed out, the wool fibre contains a basic principle capable of combining with acid bodies, and in wool dyeing with the colouring matters under discussion, this combination occurs between the sulpho-acid of the dye-stuff and the basic principle of the wool fibre.

This points to the fact that the dye-stuffs of this class do not combine with the wool in the form in which they are supplied to the dyer as sodium salts, which is shown by a property that many if not all of them possess, of not dyeing the wool fibre in a neutral bath. If a piece of wool be immersed in a solution of, say, a scarlet or indigo extract, which is neutral it is not dyed. The dye-liquor may penetrate thoroughly throughout the fabric, but if the piece of wool be lifted out, and allowed to drain, nearly all the liquor will drain away, and leave the wool nearly if not quite white, showing that the dye-stuff in the form in which it is sold has no affinity for the wool fibre. If now a few drops of sulphuric acid be added to the dye-liquor the wool will become dyed. The sulphuric acid liberates the free sulpho-acid of the dye-stuff, and this is now in a form to combine with the wool fibre, which it does. This is the fundamental principle underlying the acid method for dyeing wool with the acid group of colouring matters.

The practical application of the principle laid down above is a (p. 068) matter of simplicity compared with the other methods of dyeing. The composition of the bath is given above. It is best to enter the wool at from 150 deg. to 160 deg. F. and then to raise the temperature slowly to the boil. This method of proceeding gives time for the free colour acid of the dye to be liberated from the dye-stuff on the one hand, and for its combination with the wool fibre on the other. In dyeing pale tints with acid dye-stuffs it is a good plan not to add the acid until after the goods have been entered into the bath and worked for a short time to enable them to become impregnated with the dye-liquor; the acid may be then added, and the dyeing may be finished as usual.

By this plan of working more even dyeings can be obtained than by simply entering the goods direct into an acidified dye-liquor.

Any kind of acid may be employed, but generally sulphuric acid is used, partly because it is cheap, and partly because it is the commonest acid known. Acetic acid is also used in many cases.

Fourth Method.—We now come to the fourth method of dyeing wool. Strictly, perhaps, it is not a single method, but a group of methods, which are used to supply a certain class of dye-stuffs to the wool fibre; but as the governing principle depends upon the peculiar property of the dye-stuffs now to be noticed, which underlies all the variations of the process of dyeing, it has been thought better to speak of the fourth method rather than to subdivide further, in which case the fundamental principle might be lost sight of.

The class of dye-stuffs included in the fourth group was named by Bancroft the "adjective" group, because they require the aid of a second body, named the mordant, to properly develop and to fix the colour of the dye-stuff on the wool. It is sometimes known as the "mordant dye-stuff" class, and this is perhaps its best name. This (p. 069) group of colouring matters comprises dye-stuffs of both natural and artificial origin, the latter of which are getting very numerous and valuable, and bid fair to displace the natural members of the group. With but few exceptions the adjective dye-stuffs are not colouring matters of themselves, i.e., they will not dye wool or other fibres by themselves. Some are coloured bodies, such as fustic, logwood, Persian berries, Anthracene yellow, etc., but many are not so, and some possess but little colour, which, moreover, gives no clue to the colours that can be developed therefrom.

All the colouring matters of this class possess either a distinctively acid character, or belong to the class of phenols, which, while not being true acids, still possess weak acid functions that enable them to combine with bases like acids. These bodies have the property of combining with bases and metallic oxides, such as soda, potash, iron, alumina, chrome, tin, nickel, cobalt, etc., forming a series of salts. Those of soda and potash are usually soluble in water, while those of the other metals are insoluble, and are usually of strong colour. It is on this property of forming these insoluble coloured bodies, colour lakes, as they are called, that the value of the adjective dye-stuffs in dyeing depends.

The group of adjective colouring matters may be subdivided into two divisions, not depending upon any differences in the mode of application, but upon certain differences in the results they give. Perhaps the best example of an adjective dye-stuff is Alizarine. This body has a faint red colour, but of itself possesses absolutely no colouring power. When, however, it is brought into combination with such metallic oxide as alumina, iron and chrome, then it forms coloured bodies, the colour of which varies with the metal with which it is in union, thus with alumina, it is a bright red; with iron, a dark violet, almost black; with chrome, a deep red; with tin, a (p. 070) scarlet; and so on. This is a representative of the true adjective dyes, which comprise most of the so-called Alizarine dye-stuffs, and logwood, fustic, and most of the natural dye-stuffs. Another division of the group includes a few colouring matters of recent introduction, like Azo green, Alizarine yellow, Galloflavine, Anthracene yellow, Flavazol, etc., which, while forming insoluble colour lakes with metallic oxides, do not give different colours with different metals.

This class of dye-stuffs, owing to their forming these insoluble colours, gives really fast colours, capable of resisting lengthened exposure to light and air, and resisting washing, acids and alkalies. Of course there are differences between the various members of the group in this respect, and even the resisting power of an individual member depends a good deal on the metal with which it is combined, and the care with which the process of dyeing has been carried out.

In the dyeing of these adjective dye-stuffs, upon the various fibres, and on wool in any particular, the object is to bring about in any convenient way the formation on the fibre of the metallic combination of the colouring principle and the mordant, and it is obvious that if a satisfactory result is to be obtained, then this must be done in a very thorough manner. There are three ways in which this combination of colouring principle and mordant may be brought about in dyeing wool with these bodies, we may either mordant the wool first, and then apply the dye-stuff, or we may impregnate the wool with the dye-stuff first, and then fix or develop the colour afterwards, or, lastly, we may carry on both operations in one process. Each of these methods will now be discussed, and their relative advantages pointed out.

The mordanting method is one of the most generally useful. It consists in first causing a combination of the metal with the wool fibre. (p. 071) This is carried out by boiling the wool in a solution of the metal, such as bichromate of potash, chrome alum or chrome fluoride when chrome is to be used as a mordant, with alum or sulphate of alumina when alumina is required to be deposited on the fibre, and with copperas when iron is to be the mordant. It is best to add a little oxalic acid, cream of tartar, or tartaric acid to the mordanting bath, which addition helps in the decomposition of the metallic salt by the wool fibre, and the deposition of the metallic oxide on the wool. With bichromate of potash, sulphuric acid is often used, much depending upon the character of the mordant required. Some dye-stuffs, such as logwood for blacks, work best when the wool is mordanted with chromic acid, which is effected when sulphuric acid is the assistant mordant. Other dye-stuffs, such as fustic, Persian berries and Alizarine yellow, are best dyed on a basic chrome mordant, which is effected when tartar or oxalic acid is the assistant mordant used, or when some other form of chrome compound than bichrome is employed.

The actual mordanting is done by boiling the wool in a bath of the mordant, the quantity of which should be varied according to the particular mordant that is being employed and to the quantity of dye-stuffs which is to be used. It is obvious that for a fixing deep shade of, say, Alizarine on the wool, a larger quantity of mordant will be required than to fix a pale shade; sometimes this point is overlooked and the same amount of mordant employed for pale or deep shades. The best plan of carrying out the mordanting is to enter the wool in the cold bath or at a hand heat, and then raise to the boil and continue the boiling for one hour; of course the goods should be kept turned over during the process to facilitate the even mordanting of the wool. A great deal of the success of dyeing with the dye-stuffs now under consideration depends upon the efficiency with which the (p. 072) mordanting has been carried out. If this is at all unevenly done then no amount of care in the succeeding dyeing process will lead to the development of an even dyeing. After the mordanting is finished the goods should be rinsed with water, but it is not necessary to dry them.

The next stage in the process is the actual dyeing operations, which is done by immersing the mordanted wool in a bath of the dye-stuff or mixture of dye-stuffs.

The fundamental principle is to bring about the combination between the colouring principle of the dye-stuff and the metallic oxide which has been deposited on the wool in the previous mordanting process. As neither of these bodies, however, is very energetic it follows that the action must be a slow one, and, therefore, time is a highly important factor in the dyeing of wool by the mordanting process. The combination between the dye-stuff and the mordant is influenced also by temperature, and is most active at the boiling point of water. It is, therefore, needful to conduct this operation at that temperature, but it would be a wrong way to introduce the mordanted material into a boiling bath of the dye-stuff; nothing would conduce to uneven dyeing so much as that course. The best method of working, which, moreover, is most particularly applicable to the series of Alizarine dye-stuffs, is to enter the goods in a cold bath of the dye-stuff, and to work them for a short time to get them thoroughly impregnated, a condition which is essential if even dyeing is the goal aimed at, then to raise the temperature of the bath gradually to the boil, the goods being in the meantime well worked. The dyeing is continued for from one to one and a half hours at the boil.

It is important in dyeing by this process, especially when using Alizarine, to keep the temperature of the bath as uniform as possible, and the goods well worked. Alizarine, and some other members of (p. 073) this class, are rather sensitive to heat, and if a dye-vat be hot at the bottom and cold at the top uneven dyeing is sure to be the result; this is due to the greater affinity of the Alizarine for the mordant at the high than at the low temperature, and thus more is fixed on to the wool. The remedy for this is to so construct the heating arrangements of the vat that the temperature shall be as uniform as possible, while the goods should be kept continually turned over, and every portion of them brought into intimate contact with the dye-liquor. The continuance of the dyeing operations for one and a half to two hours after the vat has reached the boil is necessary to properly develop and fix the colour on the fibre; a short boil leaves the goods of a poor shade, without any solidity about it, and the colour is loose, while a longer boil brings up a solid shade and a fast colour.

Although it is not absolutely necessary to add any acid to the dye-bath during the dyeing operations, yet as the Alizarines and most of this class of dye-stuffs dye better in a slightly acid bath it is advisable to add a small quantity of acetic acid, say about one pint to every 100 lb. of goods; this serves to correct any alkalinity of the water, which may be due to its containing any lime. Dye-stuffs of the acid class, such as indigo extract, Cloth red, Acid magenta, etc., may be used along with the Alizarine dye-stuffs, in which case the addition of acid to the dye-bath becomes necessary, but too great an excess of acid should be avoided, as it interferes somewhat with the dyeing of the mordant dyes.

This is by far the best and most generally used method of applying these mordant dyes. It is not a costly process, being indeed economical, as it only requires just the right amounts of drugs and dye-stuffs, and there is the minimum loss of material in the mordanting and dye-baths. Shades can be brought up with the greatest ease, although it is well in the dyeing to add rather less dye-stuff than is (p. 074) actually required, and to add more when it is seen how the shade is coming up. The labour is the most important item in the mordanting and dyeing method.

The proportions of material used to the weight of the wool are: Of bichromate of potash, 3 per cent. for full shades, and 1 per cent. for pale shades; of fluoride of chrome, the same quantities; of acetate of chrome, according to the strength of the solution used; of alum, 10 to 20 per cent.; of sulphate of alumina, 5 to 10 per cent.; of copperas, 5 to 10 per cent.; of tartar, 1-1/2 to 2-1/2 per cent.; of oxalic acid, 1 to 1-1/2 per cent.; of sulphuric acid, 1 per cent.; of argol, 2-1/2 to 5 per cent.; of tartaric acid, 1 to 1-1/2 per cent.; but of course in an article like this it is impossible to give definite quantities.

Second Method. Stuffing and Saddening.—This method consists in first treating the wool with a solution of the dye-stuff, and then with a solution of the mordant required to develop and fix the colour. This method is more particularly applicable to such dye-stuffs as camwood, cutch, logwood, madder, fustic, etc., the colouring principles of which have some affinity for the wool fibre and will directly combine with it. It is not suitable for the application of the Alizarine colours. The saddening may be and is commonly done in the same bath, that is, after the wool has been stuffed it is lifted, the mordant—copperas, bluestone, bichrome, or alum—is added, and the wool is re-entered into the bath. This cannot be considered a good method of working; the shades obtained are full and deep and fairly fast, but there is usually a considerable loss of colouring matter, as the wool in no case abstracts the whole of the dye-stuff from the bath; what excess is left combines with the mordant when the latter is added, forming an insoluble colour lake, which falls down to the bottom of the dye-vat and is wasted, or it may go upon the wool in (p. 075) a loose, unfixed form, and cause it to rub badly and come off in milling. Then it is rather difficult to dye to shade, much of the result depending on conditions over which the dyer has little control. Working as he does with dye-stuffs of unknown colouring power, which may vary from time to time with every fresh batch of material, it is evident that, although the same quantities may be used at all times, at one time a deeper shade may be obtained than at another, and as it is impossible to see what is going to be the result, and if by mischance the shade does not come deep enough it cannot well be rectified by adding a quantity of dye-wood to the bath, because the mordant in the latter will prevent the colouring matter from being properly extracted, and only a part of that which is extracted is fixed on the wool, the rest being thrown away in the dye-bath, and partly on the particles of wood themselves, when logwood, camwood, etc., are used in the form of chips or powder. Dyers being well aware of this, are in the habit when mistakes occur of bringing up to shade with soluble dye-stuffs—archil, indigo extract, and such like.

This method, as stated above, is very wasteful, not only of dye-stuffs, but of mordants. In no case does the wool absorb the whole of the colouring matter from the bath, the unabsorbed portion goes down to the bottom of the bath when the mordant is added, so that when the dyeing is finished, the dye-bath is charged with a large quantity of colouring matter in an unusable form which has to be thrown away, thus at once adding to the pollution of the river into which it is run, and to the cost of the process of dyeing. As attention is being directed more and more to the question of the prevention of pollution of rivers, and as the waste liquors from dye-works add to the apparent pollution to a very considerable extent, dyers will have to develop other modes of dyeing than that of stuffing and saddening in one bath.

The principle of dyeing by stuffing and saddening may be carried (p. 076) out by the use of two separate baths; in fact, it is done in the case of dyeing a cutch brown from cutch and bichromate of potash. The goods are first treated in a bath of the dye-wood for a short time, then rinsed, and the colour is developed by padding into a saddening bath of the mordant. By this method the baths, which are never quite exhausted, can be retained for future use, only requiring about 1/2 to 3/4 of the original quantities to be added for each succeeding batch of the goods, in fact, in some cases, as in cutch, old baths work better than new ones.

The advantage attached to this method of working is that arising from economy of dye-stuff and mordant, and the reduction of the pollution of the stream on which the works are situated. The disadvantages are that the cost of labour is increased by there being two baths instead of one, and that the shades obtained are not always so full as with the one-bath method. This, of course, can be remedied by running the goods through the baths again, which, however, adds to the cost of the process, but there is this much to be said, the shade can be better brought up than by the one-bath process. In some cases the methods of mordanting, dyeing and saddening are combined together in the dyeing of wool, thus, for instance, a brown can be dyed by first mordanting with bichrome, then dyeing with camwood and saddening in the same bath with copperas. The shades obtained are fairly fast and will stand milling. The disadvantages of this process are the same as those attached to the dyeing and saddening in one bath.

Now we come to the last method of dyeing wool with mordant and colours, that in which the operation is carried out in one bath. This can only be done in those cases where the colour lake that is formed is somewhat soluble in dye-liquors, which usually have slightly acid properties; or where the affinity between the two bodies (colouring matter and (p. 077) mordant) is too great. This method can be carried out in, for instance, dyeing a cochineal scarlet with tin crystals, a yellow from fustic and alum, a black from logwood and copperas and bluestone, a red from madder and bichrome, and the dyeing of the Alizarine colours by the use of chrome fluoride, etc.

The shades obtained are usually not so deep as those got by the mordanting and dyeing process, but are frequently nearly so. In some cases, as in dyeing with fustic or logwood, it gives rather brighter colours, due to the fact that the tanning matters present in the dye-stuffs is not fixed on the wool, as is the case with the mordanting method, but is retained in the dye-bath. For dyeing with logwood and copperas or bluestone the process is not a good one, as it does not give as full shades as by the ordinary process. For dyeing with the Alizarine colours, using chrome fluoride as the mordant, it can be applied with fair success. There are advantages in the saving of time and labour and in the amount of steam required, all of which are important items in dyeing.

It is rather troublesome to match off by this process, but it can be done. For light shades the process will be found very useful, as these cost less than by any other process. The dye-baths may be retained for future use, although in process of time they become too dirty for use, when they must be thrown away.

Level Dyeing.—The first condition for successful dyeing is that the fibres to be treated are absolutely clean. A careful washing is not enough for this purpose. Cleanliness is undoubtedly the condition which the fibre must possess to enable the dye to hold on and not to come off the fibre, this latter causes a loss of dye-stuff, soils the whites, and gives rise to trouble between the dyer and finisher; it is also the condition for making the dye go on the wool evenly. The (p. 078) washing must be done at the boil, so that the fibre is well wetted out and all the air bubbles adhering to it are driven out. But this is not enough; it must be accompanied by a scouring operation, not only in the case of fibres of which the dyer does not know whether they have been scoured, but also when they have already been scoured and bleached. The kind of scouring that the fibres receive in this case need only be of a comparatively light character, but it must never be omitted, even for dark shades, as the traces of grease which the fibre contains are the causes of nearly irremediable stains in the dyeing operations. Even in dyeing black wool it is of the greatest importance to have the fibre suitably scoured.

The fatty matters which the fibre contains may belong to the components of the fibre itself and be natural matters, but in the case of wool yarns and cloths they are mostly dressing oils, from which the dyer cannot be too anxious to free the wool before dyeing. Some practical methods of preparatory treatment of the fibres before dyeing may therefore be described here with advantage.

Cotton is boiled off at actual boiling heat for two hours, with 8 per cent. of its weight of carbonate of soda and a little soft soap, which treatment is sufficient for dark colours.

For light colours it is necessary that the cotton be bleached. Wool is scoured with soda and soap in the proportion of 10 lb. soda and 2 lb. Marseilles soap for 100 lb. wool. Silk is scoured by boiling for one and a half hours in a boiling bath with 30 per cent. of its weight of soap. For light colours a second boiling should be given, with 15 per cent.

The careful cleaning of wool previous to dyeing is of exceptional importance. Raw wool is cleaned with carbonate of soda and ammonia. For 50 lb. wool to be cleaned 6 lb. carbonate of soda and 1-1/2 lb. (p. 079) ammonia are added to a bath of 150 gallons water. The wool is laid down in it for twenty minutes at 35 deg. C., taken up, squeezed, treated for fifteen minutes in another bath, with 5 lb. carbonate of soda and then rinsed. The first bath must be renewed as often as possible, because it contains all the impurities. In the case of woollen yarn 30 lb. require two tubs of 40 gallons capacity. The first tub is to contain 35 gallons water and 2 lb. ammonia at 10 deg. Be. After working the skeins for three minutes in it they are left to stand for fifteen minutes, then wrung out, and the operation is repeated in the second tub. Finally, the yarn is rinsed several times in soft water.

Woollen piece goods are treated in a large wooden tub at 40 deg. C. with 4 lb. carbonate of soda and 2 lb. carbonate of ammonia for 80 lb. material. The pieces are moved about for twenty minutes, laid down in the bath overnight, again turned for ten minutes and hydro-extracted. They may also be handled for forty minutes in a bath of 2 oz. ammonia for 100 lb. wool at 60 deg. C., and then for twenty minutes in clear water at 60 deg. C.

After wetting or preparatory treatment, it will be best to proceed immediately to dyeing; if the fibres be left in a heap for too long a time, there is danger that they may become heated, or at least that the moisture may be irregularly distributed by the occurrence of partial drying, causing an uneven fixation of the colour in the first stages of dyeing. The first two conditions of successful dyeing are, therefore, a suitable wetting out and scouring. The dyer, however, must not be less careful to see that the dye-bath is what it ought to be.

Whenever possible the dye-stuff must be dissolved separately, or at least the bath not entered before the dye-stuff is well dissolved. Artificial dye-stuffs require particular attention to this point, because the presence of undissolved particles is the cause of (p. 080) irregularities, such as streaks, or, at least, specks. The solution is mostly made hot as follows: After pouring water at 180 deg. F. upon the dye-stuff, stir gently, strain through flannel or through a very fine sieve, and pour more water upon the residue until nothing more is dissolved. As is well known, the artificial dye-stuffs often contain insoluble matter, resins, etc. It is therefore advisable to use only soft water for this operation.

The solutions of artificial dye-stuffs are ordinarily made at the rate of 1 to 5 lb. per 10 gallons of water, 2 lb. being the proportion mostly employed. This depends more or less on the solubility of the dye-stuff. Old solutions sometimes contain crystals of the dye-stuff which have separated out. These should be redissolved by heating before the solution is used. But it is best to make only such a quantity of solution as will suffice for immediate requirements.

With paste colours care should be taken to keep them in closed vessels in such a manner that they will not become hard by evaporation, and they should not be kept in any place where they are likely to freeze in winter time. In such an event it is not an uncommon circumstance for the casks or other vessels containing them to burst, with a consequent loss of dye-stuff. Before any of the paste is withdrawn from the cask, it is advisable to stir well up with a wooden stirrer.

In adding dye-stuff during the actual dyeing operation, it is advisable to add the dye-stuff to the bath in two or three portions, always taking out the goods before adding each lot of dye-stuff, and stirring up the contents of the bath before re-entering the goods. Another important condition of obtaining a level dyeing is to proceed slowly, beginning with a weak bath at a moderate temperature, and rising gradually to a boil. If necessary to retard the dyeing from the commencement, then an assistant mordant is added to the dye-bath, in the shape of soda crystals or phosphate of soda for the benzidine (p. 081) colours on cotton; bisulphate of soda or Glauber's salt in dyeing with azo colours or acid colours on wool; or tartar may be used in most cases with good effect, causing the wool to have a softer feel. Finally, the evenness of the dyeing is much increased by the frequent turning over of the material in the dye-bath, so managing this in the case of wool as to avoid felting.

When dyeing with a mordant, the dyer should see that the mordanting operation is thoroughly well done, for as much care is required for the mordanting as for the actual dyeing; in fact, if anything, the mordanting should be done with rather more care, as if it be at all defective no amount of care in the following dyeing operations will ensure a level dyeing. Chrome mordanted wool should be dyed without delay, as it is rather sensitive to light, especially the yellow sort, which gradually changes into the green sort of chromed wool.

One peculiarity of dyed wool is that it will continue to take up colour after it is removed from the dye-bath, especially if it contains any of the hot dye-liquor, therefore it is very desirable to wash the wool as soon as possible after its removal from the dye-bath. It is best, however, not to take the wool out of the hot bath, but to leave it in until the bath becomes cool, and then to take it out, by this means the colour becomes deeper and more solid looking, and is faster on the wool.

One cause of irregular dyeing may be mentioned, as it is occasionally met with, namely, the presence of foreign fibres in the goods, cotton in wool fabrics, and even of different varieties of the same fibre. All dyers know that dead or immature cotton will not dye up properly, a fact or defect more especially met with in indigo dyeing than probably in any other colour. Then wools from different breeds of sheep vary considerably in their dyeing power. Fine wools take up more colour (p. 082) than coarse, and, consequently, even from the same bath, will come out a deeper shade; if a fabric, therefore, contains the two kinds of cotton, or the two kinds of wool, they will not dye up evenly.

In the preceding sections brief notes have been given about the principal methods of dyeing wool, with some indications of the dyes which can be used under each method. In the succeeding sections will be given a number of recipes showing how, and with what dye-stuffs, various colours, shades and tints can be dyed upon wool. It will be understood that these recipes are applicable to all kinds of woollen fabrics, loose wool, slubbing, yarns in any form, woven worsted or woollen cloths, felts of any kind, etc., all these different forms require handling in a different way; it would not do, for instance, to treat a quantity of slubbing in the same way as a piece of worsted cloth, while hanks of yarn require a different mode of handling to a quantity of hat bodies. The different kinds of woollen fabrics require to be dealt with in different kinds of machines, and this has already been dealt with in the chapter on Dyeing Machinery and Dyeing Manipulations.

To describe and illustrate the application of all the various woollen dye-stuffs, whether of natural or artificial origin, and to show the great variety of shades, etc., which can be obtained with them, either all one or in combination, would require not one, but many volumes of the size that this present work is intended to be. Therefore, it becomes necessary to make a selection from the best-known and most used of the various dyes, and illustrate their application by a number of recipes, all of which, unless otherwise stated, are intended to be for 100 lb. weight of woollen material of any kind. It may also be pointed out that, as a rule, the recipes may be applied to the dyeing of fabrics made with other animal fibres than the wool of the sheep, as, for alpaca, cashmere, camel-hair, hare or rabbit fur, etc., (p. 083) inasmuch, as, with the exception of silk, all animal fibres practically possess the same dyeing properties.

It will be convenient to point out here that a very large proportion of the shades dyed on wool and other fabrics are obtained, not by the use of a single dye-stuff, although this should always be done, whenever possible, but by the combination of two or more dye-stuffs together in various proportions. It is truly astonishing what a great range of shades can thus be dyed by using two or three dyes suitably mixed together, and one of the things which go to making a successful dyer and colourist is the grasping of this fact by careful observation, and working accordingly. Dyers will find much assistance in acquiring a knowledge of colour and colour mixing from the two little books on Colour, by Mr. George H. Hurst, and the Science of Colour Mixing, by Mr. David Paterson, both issued by Messrs. Scott, Greenwood & Co., the publishers of the present work.

Black on Wool.—Until within a comparatively recent time black was dyed on wool solely by the use of logwood, combined with a few other natural dye-stuffs, such as fustic, indigo, etc., but of late the researches of colour chemists have resulted in the production of a large number of black dyes obtained from various coal-tar products. These have come largely into use, but still, so far they have not been able to entirely displace logwood, chiefly on the score of greater cost, the use of the natural dye still remaining the cheapest way of producing a black on wool; although the blacks yielded by some of the coal-tar black dyes are superior to it in point of intensity of colour and fastness to scouring, acids and light, as well as being easier to dye.

Blacks may be obtained from logwood by several methods, either by previous mordanting of the wool or by the stuffing and saddening methods, or by the one-bath process. The following recipes will (p. 084) show how these various methods are carried out in practice:—

Chrome Logwood Black.—The wool is first mordanted by boiling for one and a half hours with 3 lb. bichromate of potash and 1 lb. of sulphuric acid, working well the whole of the time. It is not advisable to exceed the amounts of either the bichromate or the acid here given, these quantities will result in a full bloomy black being obtained, but any excess gives rise to greyish dull blacks, which are undesirable. After mordanting rinse well with water, when the goods will be quite ready for the dye-bath.

The dyeing is done in a bath made from a decoction of 40 lb. of good logwood. It is perhaps preferable to start cold or only lukewarm, raise to the boil and work for one hour, then lift, rinse well, and pass into a boiling bath made from 1 lb. of bichromate of potash and 1/4 lb. of sulphuric acid for half an hour. This extra chrome bath fixes any colouring matter which may have been absorbed by the wool but not properly fixed by the mordant already on, it leads to fuller shades which are faster to rubbing and milling.

The mordanting bath may be kept standing and used again for fresh lots of wool, in which case it is only necessary to add 2-1/2 lb. of bichromate of potash and 1 lb. sulphuric acid to the bath for each additional lot of wool that is being dealt with. Old mordant baths work rather better than new ones, but the use cannot be prolonged indefinitely, there comes a time when the bath gets too dirty to use and then it must be thrown away.

During the operation the bichromate of potash becomes more or less decomposed and there is formed on the wool fibre a deposit of chromic acid and chromic oxide, this deposit forms the mordant that in the subsequent dye-bath combines with and fixes the colouring matter, the haematoxylin of the logwood, and develops the black on the wool.

In place of sulphuric acid, hydrochloric acid can be used with (p. 085) some advantage as regards the proportion of bichromate decomposed, and therefore an increase in the amount of chromium oxide deposited on the wool.

This gives a deep blue black, somewhat wanting in bloom. The following recipe gives a much bloomier black, but is rather more expensive to dye.

Chrome Logwood Black.—Mordant by boiling in a bath containing 3 lb. bichromate of potash and 7 lb. tartar. Dye and otherwise treat as in the last recipe; 4 lb. of tartaric acid used in place of the tartar, gives rather brighter and bloomier shades. The use of so-called tartar substitutes is not to be recommended, they give no better results than does sulphuric acid and are much dearer to use.

A somewhat greener shade of black than is yielded by either of the above two recipes is the following:—

Chrome Logwood Black.—Mordant the wool in a bath containing 4 lb. oxalic acid and 3 lb. bichromate of potash, afterwards dyeing as in the first recipe.

All the above recipes give blacks of a bluish tone, which on the whole have a good bloomy and solid appearance. Often what is called a jet black is wanted, this can be obtained by following the recipe given below.

Chrome Logwood Jet Black.—Mordant the wool by any of the methods given above. The dyeing is done in a bath made from 40 lb. logwood and 5 lb. fustic, working as described in the first recipe. Using these properties a good jet black is obtained, which is quite satisfactory on the score of solidity and fastness. It is not advisable to exceed the quantity of fustic here given, or otherwise the black will have a tendency to assume a greenish tone that is not at all desirable. This greening becomes more marked when from 7-1/2 to 10 lb. of fustic is used, or if alum be added to the mordant along with the bichromate of potash.

Chrome blacks are the best blacks which can be obtained from (p. 086) logwood. They have, however, a tendency to turn green on exposure to the weather, which tendency seems to be most prevalent in those blacks in which sulphuric acid has been used as the acid constituent of the mordanting bath. The greening may be reduced to a minimum by adding to the dye-bath about 1 to 2 lb. of Alizarine. Another plan which has been followed is to give the wool a bottom with 5 to 6 lb. of camwood or peachwood, then mordanting and dyeing us usual.

Logwood Black on Wool.—Boil first for one hour with a decoction of 8 lb. camwood, then lay down for fifty minutes in a boiling bath of 3 lb. bichromate of potash, 1 lb. alum, 1 lb. tartar. It is a good plan to allow the goods to hang overnight.

The dye-bath is prepared with 45 lb. logwood, 8 lb. fustic, 4 lb. sumac. Dye one hour at the boil, wash and dry.

Indigo Black.—This is sometimes called woaded black, and has an excellent reputation as a fast black. It is dyed by first giving the wool a medium blue bottom in the indigo vat by the method of vat dyeing, which will be described later on, and then dyeing by either the second or third recipe given above. The use of sulphuric acid is rather to be avoided in dyeing an indigo vat with chrome and logwood, as the chromic acid set free during the process is likely to attack and by destroying the indigo to materially reduce the intensity of the blue bottom. Or, after blueing in the vat, the black may be dyed or topped on by the process with copperas, which will be described below.

Iron Logwood Black.—Mordant the wool by boiling one and a half to two hours in a bath made with 5 lb. copperas, 2 lb. bluestone, 2 lb. alum, and 10 lb. argol. The dyeing is done in a bath of 50 lb. logwood.

It is not advisable to use more argol than is here given, for (p. 087) although a little excess will not materially affect the beauty or brilliancy of the resulting shade, yet such excess is wasteful, and makes the dyeing cost more than it otherwise would. On the other hand, too little will cause the shade to become greyish in tone and wanting in solidity. The copper sulphate (bluestone) added increases the fastness of the finished black to light, the best proportions to add are from 2 lb. to 4 lb. for 100 lb. of wool. The shade obtained in the above recipe is of a bluish-violet hue, if a jet black be wanted, add 5 lb. of fustic to the dye-bath. Another and very common method of working is the "stuffing and saddening" process, given in the next recipe.

Iron Logwood Black.—Make a bath of 50 lb. logwood, 6 lb. fustic, and 1 lb. sumac. Work the wool in this for one hour at the boil, lift, allow the bath to become cool, then add 6 lb. of copperas (ferrous sulphate) and 2 lb. bluestone; re-enter the wool, raise the temperature to the boil, and work half an hour, then lift, wash and dry. On the whole the first method is the most economical and yields the best blacks, fastest to rubbing.

The iron-copper-logwood blacks are not so fast to acids as the chrome-logwood blacks, but they are rather faster to light and air, and equally so to scouring and milling.

One-bath methods of dyeing blacks are sometimes preferred by wool dyers. Of these the following is an example.

Logwood Black.—Make a dye-bath with 50 lb. logwood, 5 lb. fustic, 6 lb. copperas, 2 lb. copper sulphate, and 4 lb. oxalic acid. Enter the goods and work at the boil to shade. The oxalic acid is added for the purpose of retaining the logwood-iron-copper black lake, which is formed on mixing the various ingredients together in solution. On boiling the wool in the liquor the fibre gradually extracts out the dye matter and becomes dyed. The use of some of the so-called (p. 088) "direct blacks" (noir reduit, Bonsor's black) is based on the same principle.

These dyes are mixtures of logwood, fustic or other dye-stuff with copperas, bluestone and oxalic acid, and only require adding to water to make the dye-bath. This method of working enables logwood to be used in conjunction with dihydroxynaphthalene and some other coal-tar derivatives to obtain blacks of good solidity and much faster to light, air, acids and scouring than the ordinary logwood blacks.

Another recipe for a one-bath logwood black, using the extracts in place of the dye-wood itself, is the following:—

Logwood Black.—Prepare a dye-bath with 12 lb. logwood extract, 2 lb. fustic extract, 6 lb. copperas, 4 lb. bluestone, 3 lb. oxalic acid, 2 lb. tartar. Boil the goods in this for one hour.

Some dyers use the dye-woods and prepare from them a decoction by boiling in water; in some respects this is the most economical plan, only the dyer has to get rid of the spent dye-wood from which the colouring matter has been extracted, and this is not always an easy matter. Some dyeing machines (Smithson's) have been devised which contain as one of their features a dye-wood extractor, in which the extraction of the colouring matter of the wood proceeds at the same time as the dyeing. Good results are got with such machines, although they leave something to be desired.

Many dyers use the dye-wood extracts which are now made on a large scale. These are for the dyer much more convenient to use, although naturally rather more costly. They are approximately five times the strength of the dye-wood, but they vary very greatly in this respect.

Logwood blacks can be readily distinguished from nearly all other blacks, in that by treatment with moderately strong hydrochloric acid they turn a bright red.

No other natural dye-stuff is used in the dyeing of black than these here given.

Of late years many black dyes derived from coal tar have been (p. 089) placed on the market. Among these may be enumerated the Acid Blacks of Messrs. Bead Holliday & Sons; the Naphthol and Naphthylamine Blacks of Leopold Cassella & Co.; the Victoria Blacks of the Farbenfabriken vorm, Fr. Bayer & Co.; the Wool Blacks of the Actiengesellschaft fuer Anilin Fabrikation; the Azo Blacks of the Farbwerke vorm, Meister, Lucius & Bruning; and one or two other blacks. These blacks are dyed very simply, as will be seen from the recipes given below, showing their application in the production of blacks of a great variety of tone. None of them dye a true jet black, but generally a bluish black or a violet black, but the tone may be readily changed to a jet or dead black by the addition of a little orange, yellow or green dye-stuff.

They give blacks of a very solid appearance and very bright in tone, and have the advantage over the logwood blacks of leaving the wool more supple and less liable to be felted. Moreover, as a rule they are faster to acids, alkalies and milling than are the logwood blacks, and as regards fastness to light they excel that dye-stuff. Unfortunately they are more costly to use, which tells against their entirely displacing logwood in dyeing blacks on wool.

Still, year by year their use is increasing, and as their price becomes less their employment will yet further extend. They may be combined with logwood, as they will dye with equal facility on mordanted and unmordanted wool.

Violet Black on Wool.—Make the dye-bath with 4 lb. Acid Black B, or Acid Black B B, 3 lb. sulphuric acid, and 10 lb. Glauber's salt. Work at the boil for one hour. The B brand of these blacks gives shades slightly redder in tone than the B B. The blacks are quite fast to light and acids, but not to soaping.

Blue Black on Wool.—Dye as in the last recipe, but use Acid (p. 090) Black S. This dye-stuff produces bluer shades of black than either B or B B, and they are faster to soaping.

Jet Black on Wool.—Make the dye-bath with 4-1/2 lb. Acid Black S, 1/2 lb. Fast Yellow F Y, 3 lb. sulphuric acid, and 10 lb. Glauber's salt. This shows how, by the addition of a little yellow dye-stuff, the blue shade may be changed to a full jet black.

Blue Black on Wool.—The dye-bath is made with 4-1/2 lb. Naphthol Black B (or 6 lb. Naphthol Black 3 B), 4 lb. sulphuric acid, and 10 lb. Glauber's salt. Work at the boil for one hour, then lift, wash and dry. The Naphthol Blacks have long been used in wool dyeing, and give excellent results, the 3 B brand dyeing much bluer shades than the B brand. There is also a 4 R brand giving violet blacks. These blacks are quite fast to acids and alkalies, are fast to light, and resist washing very well, the B brand being the fastest. The following recipe shows how a full jet shade can be obtained for these blacks:—

Jet Black on Wool.—Prepare the dye-bath with 4-1/2 lb, Naphthol Black B, 1 lb. Naphthol Green B, 1/4 lb. Indian Yellow, 4 lb. sulphuric acid, and 10 lb. Glauber's salt.

Blue Black on Wool.—Make the dye-bath with 5 lb. Anthracite Black B, 10 lb. Glauber's salt, and 5 lb. bisulphate of soda, working at the boil for one hour. Anthracite Black does not require a bath so acid as do some other coal-tar blacks. The shade obtained is a full blue black, which is fast to acids; alkalies turn it a little bluer, and soaping causes some loss of colour.

Violet Black on Wool.—Make the dye-bath with 5 lb. Anthracite Black R, and 10 lb. bisulphate of soda. The black thus obtained is a good one, fairly fast to acids, alkalies and soaping.

Dead Black on Wool.—Make the dye-bath with 6 lb. Anthracite Black R, 1 lb. Anthracene Yellow C, and 10 lb. bisulphate of soda. Work at (p. 091) the boil for one hour, then lift, add 3 lb. fluoride of chrome and work again at the boil for twenty minutes. This black is a very fine one, and is very fast.

Violet Black on Wool.—Make the dye-bath with 4 lb. Naphthylamine Black D, 10 lb. Glauber's salt, and 5 lb. acetic acid. This black is pretty fast to acids, alkalies and light, but is somewhat loose to soaping, and, therefore, cannot be used for black goods that have to be strongly milled. Naphthylamine Black 4 B dyes somewhat bluer shades than the B brand.

Blue Black on Wool.—Prepare the dye-bath with 6 lb. Victoria Blue Black, 20 lb. Glauber's salt, and 1-1/2 lb. acetic acid, working at the boil for one hour. A fine blue black, is obtained which is quite fast to acids, washing and light.

Greenish Black on Wool.—The dye-bath is made with 3 lb. Victoria Black Blue, 2 lb. Fast Yellow F Y, 20 lb. Glauber's, salt, and 1/1-2 lb. acetic acid. The dyeing is done at the boil and takes about an hour. This shade has a good full tone, and is fast.

Jet Black on Wool.—Make the dye-bath with 4 lb. Victoria Black B, 1/2 lb. Fast Yellow F Y, 10 lb. Glauber's salt, and 2 lb. sulphuric acid, working at the boil for one hour. A very fine shade is thus obtained, which is fast to acids, alkalies and soaping. By omitting the Fast Yellow a blue black is obtained, while by using Acid Green instead a greener tone is given to the black. In place of the Victoria Black B the two other brands, 5 G, and G, of these blacks may be used. These give equally fast blacks of a deeper and more jet black.

Black on Wool.—Prepare a bath with 5 lb. acetic acid, 9 deg. Tw.; enter the wool for one hour, then lift and add 5lb. Naphthol Black 3 B, and 1/4 lb. Indian Yellow. Re-enter the goods and boil for one hour, wash and dry.

Many of the black dyes—Naphthol Black, Naphthylamine Blacks, (p. 092) Naphthyl Blue Black N, Acid Black B, etc.—are capable of slowly dyeing wool from neutral baths, that is, containing only Glauber's salt, or rather more quickly if a little acetic acid be present. Such dyes are very useful for dyeing heavily milled or felted fabrics, such as hat bodies for instance, as then the dye possesses greater penetrative properties and passes more into the substance of the fabric, which is, therefore, better dyed through. Also they are suitable for dyeing half-wool fabrics as will be seen on referring to the chapter dealing with the dyeing of union or cotton-wool fabrics.

It is quite possible to dye a black on wool by using a combination of acid and azo dye-stuffs, and below is given a recipe illustrating this method; it is one, however, rarely adopted.

Blue-Black on Wool.—Prepare the dye-bath with 10 lb. Glauber's salt, 2 lb. Patent Blue, 6 oz. Brilliant Orange, 4 oz. Amaranth, 4 oz. Acid Violet N, 4 lb. sulphuric acid. Enter the goods at about 150 deg. F., raise to the boil and work to shade; lift, wash and dry. It may be of interest to note that by using a mixture of Azo Rubine and Acid green good blacks can be got.

There is a range of Acid and Azo dyes which are capable of dyeing from the usual acid baths on to wool, and yet can be developed and fixed on the fibre to good, full blacks. Types of such dyes are Anthracene Chrome Black F F, Diamond Black F, Chrome Patent Black D G and D G G, Fast Chrome Black, etc. Generally the blacks dyed on wool with these dyes are very fine, have a full, bloomy appearance, and are very fast. They are much used in dyeing hat bodies and fine cloths which have to be very fast to the weather.

The method of application will be gleaned from the recipes given below.

Black.—Prepare a dye-bath with 5 lb. Chromotrop S, 1/4 lb. Azo (p. 093) Yellow, 50 lb. Glauber's salt. Work for one and a half hours at the boil, then add 4 lb. sulphuric acid. Work at the boil for another half hour, then lift. Add to the same dye-bath 3 lb. bichromate of potash. Re-enter the goods and work at the boil for half an hour, then lift, rinse and dry.

Jet Black.—Mordant the wool by boiling for one hour in a bath made from 4 lb. bichromate of potash and 3 lb. of tartar. Then rinse, and dye in a bath containing 3-1/2 lb. Diamond Black, 1-1/4 lb. Alizarine Cyanine R R R double, and 1 lb. Gambine Yellow, working at the boil for from one to one and a half hours.

Diamond Black on Wool.—Mordant by boiling for one hour with 3 lb. bichromate of potash, 1 lb. oxalic acid. Wash and dry in a bath made with 2 lb. Diamond Black, 2 lb. acetic acid. Work at 120 deg. F. for one hour, then heat to boil, and work until the dye is fully fixed. Lift, wash and dry.

A more common method of using the Diamond Black is given in the following recipe.

Diamond Black.—Prepare a dye-bath with 10 lb. Glauber's salt, 2-1/2 lb. Diamond Black, 1/2 lb. Diamond Green. Boil for an hour, then pass through a fresh bath of 2 lb. bichromate of potash for three-quarters of an hour at the boil; wash and dry.

This gives a fine jet shade of black, quite fast to a strong milling, and to light, alkalies and acids. Diamond Black by itself gives bluish shades. This dye is much used in the hat-dyeing trade.

Violet Black.—Mordant the wool by boiling for one and a half hours in a bath made with 3 lb. fluoride of chrome and 1 lb. oxalic acid, then rinse and dye in a bath containing 25 lb. Alizarine Cyanine Black G, 5 lb. acetate of ammonia, and 1 lb. acetic acid, working at the boil for one and a half hours. A fine full shade is obtained (p. 094) which is quite fast to acids, milling and light.

Brown Black.—Mordant the wool as in the last recipe, then dye in a new bath 25 lb. Alizarine Cyanine Black G, 3 lb. Anthracene Brown, 5 lb. acetate of ammonia, and 1 lb. acetic acid, working at the boil for one to one and a half hours.

Jet Black.—Mordant as in either of the above recipes, then dye in a bath containing 20 lb. Alizarine Black S W, and 2 lb. acetic acid. This black possesses a great degree of resistance to acid, alkali, milling and light, and is one of the best blacks at the disposal of the dyer.

Reddish Black on Wool.—Prepare the dye-bath containing 5 lb. Chromotrop 2 B, 10 lb. Glauber's salt, and 4 lb. sulphuric acid, work at the boil for one hour, then lift. Add to the same bath 3 lb. bichromate of potash and 1 lb. sulphuric acid, and work half an hour longer.

Blue Black.—Make the dye-bath with 6 lb. Chromotrop 10 B and 4 lb. sulphuric acid; dye, and develop the black by adding to the same bath 3 lb. bichromate of potash and 1 lb. sulphuric acid.

Jet Black.—Prepare the dye-bath with 5-1/2 lb. Chromotrop S, 1/4 lb. Alizarine Yellow G G W, 10 lb. Glauber's salt, and 4 lb. sulphuric acid. Slowly raise to the boil and work for one hour, then add to the same dye-bath 3 lb. bichromate of potash, and 1 lb. sulphuric acid, working at the boil for one hour.

These are but a few examples of how the Chromotrops (one of the most interesting series of dye-stuffs at the service of the dyer) may be used to dye blacks. They of themselves dye brilliant reds, from bright scarlet (2 R), crimson (6 B), and purple (8 B and 10 B), to maroon and clarets (S and S B). These being turned black on being chromed, give various shades—blue blacks, violet blacks, and jet blacks, which have the merit of being fast to acids, strong milling, and light in a great degree. The blue and violet blacks may be converted to jet (p. 095) shades by adding to the dye-bath some yellow dye-stuff, such as Azo Yellow, Alizarine Yellow, or Gambine Yellow, which will resist the action of the bichrome in the developing bath.

Chromotrop blacks while so very fast have the disadvantage of being expensive, but by combining them with logwood it is possible to obtain blacks that have a great degree of resistance to light, acids and milling. They are in this respect much superior to pure logwood blacks, while the cost is not prohibitive.

The following recipe will serve as an example of how these two dye-stuffs may be combined:—

Jet Black.—Make a bath with 2 lb. Chromotrop S, 15 lb. Glauber's salt, and 5 lb. hydrochloric acid. Work in this bath for one hour, then add 2-1/2 lb. bichromate of potash, and work again for half an hour, at the boil. Lift, rinse and dye in a new bath containing 25 lb. logwood, 1 lb. fustic extract and 1/4 lb. sulphuric acid, working at the boil for an hour.

Violet Black on Wool.—Dye the wool in the Chromotrop bath, and develop as in the last recipe. The final dye-bath is made with 6 lb. logwood, 8 oz. Patent Blue B, and 4 lb. sulphuric acid. By using logwood alone blue blacks can be dyed, by increasing the proportion of fustic a greener tone can be obtained, while by the use of a larger proportion of Chromotrop a redder tone of black is the result.

Jet Black.—Make the dye-bath with 20 lb. Glauber's salt, and 6 lb. Nyanza Black; when obtained is a good one and of solid appearance. Alkalies turn it red, but it is fast to dilute acid and soaping.

Black.—Prepare the dye-bath with 10 lb. Glauber's salt, 5 lb. oxalate of ammonia, 5 lb. acetic acid and 6 lb. Anthracene Chrome Black F. Work at the boil for three-quarters of an hour, or until (p. 096) the bath is exhausted of dye-stuff, then add 1-1/2 lb. bichromate of potash and 2 lb. hydrochloric acid to the same bath and work for half an hour longer.

The Anthracene Chrome Blacks, of which there are three brands, F, 5 B and F E, are excellent dyes, producing very fine blacks, and owing to the slowness of dyeing and great penetrative properties are very suitable for dyeing hat felts and other closely woven fabrics. The 5 B dyes more bluish shades than the F, while the F E brand gives full black. By combining these with Anthracene Yellow B N, Anthracene Acid Brown G, or other similar dyes, jet blacks can be got as per the following recipe:—

Jet Black.—Make the dye-bath with 6 lb. Anthracene Chrome Black F E, 5 oz. Anthracene Yellow B N, 10 lb. Glauber's salt, 2 lb. oxalate of ammonia and 5 lb. acetic acid, after dyeing, and the dye-bath, is exhausted of colour, add 1-1/2 lb. bichromate of potash and 3 lb. hydrochloric acid, and boil again for half an hour. Finish in the usual way.

One of the reasons for adding the oxalate of ammonia, is to precipitate out any lime which may be in the water in such a form that it will not react with the dye-stuff.

Fast Black.—Mordant the yarn with copperas (sulphate of iron). Dye in a bath with 5 lb. Gambine Y, 2 lb. Acid Mauve, 2 lb. bisulphate of soda. Proceed as described for full green.

Blue Black.—3-1/2 lb. Naphthylamine Black S, 10 lb. Glauber's salt, and 5 lb. acetic acid; to fully exhaust the dye-bath add 8 lb. bisulphate of soda.

Jet Black.—5 lb. Naphthylamine Black S, 1/4 lb. Fast Acid Green B N, 10 lb. Glauber's salt, and 5 lb. acetic acid, adding 8 lb. bisulphate of soda to exhaust the bath.

Blue Black.—Give a deep blue bottom in the indigo vat and dye with 2 lb. Anthracite Black B, 10 lb. Glauber's salt and 2 lb. acetic acid.

Greys on Wool.—The dyeing of greys follows very naturally after (p. 097) the dyeing of blacks, for from a broad point of view greys are simply light blacks, and any dye-stuffs that will dye black will if used in smaller proportions give greys. There is a great variety of tone among greys: reddish greys, bluish greys, greenish greys, and so on. They may be dyed in a considerable variety of ways from a large number of dye-stuffs, both natural and artificial. Of these two classes the latter gives the best result as far as regards brightness of tone, and as regards other properties the greys obtained from the artificial coal-tar colours are fully equal to those from natural dyes.

A large number of recipes are in use by dyers for the production of greys, so many that it becomes almost an impossibility to do more than give a mere fraction of them here. However, a number of representative recipes will be given, covering all classes of dye-stuffs capable of being used for the purpose, and thus forming a guide to the methods of dyeing and the proportions of dye-stuffs to be used.

Light Grey.—Dye at the boil for three-quarters of an hour, in a bath containing 1 lb. perchloride of tin, 3 lb. alum, 3 oz. indigo extract, and 2 oz. cochineal.

Slate Grey.—Mordant by boiling with 4 lb. alum and 1 lb. argol, then dye with 6 lb. logwood, 6 oz. cudbear and 3 oz. indigo extract.

Slate Grey.—Another method is to boil the wool with 10 lb. logwood, 2 lb. Glauber's salt and 1 lb. sulphuric acid for three-quarters of an hour, then lift, add 1 lb. copperas, and re-enter the wool, working at the boil for three-quarters of an hour, then lift, wash and dry.

Reddish Grey.—Boil for an hour with 10 lb. fustic, 11 lb. cutch, 1/2 lb. bichromate of potash and 1-1/2 lb. copperas.

Pearl Grey.—Give a light blue ground in the indigo vat, then dye in a new bath with 2 lb. muriate of tin and 3/4 lb. cochineal, working at the boil to shade.

Silver Grey.—Prepare a bath with 3/4 lb. tannic acid; work for (p. 098) an hour in a warm bath, then sadden with 3 lb. nitrate of iron to shade, then lift, wash and dry.

Pearl Grey.—Prepare a bath with 3 lb. fluoride of chrome and 4 lb. Alizarine Bordeaux B. Enter into the bath when cold, then heat to the boil and work for one and a half hours, then lift, wash and dry.

Silver Grey.—The dye-bath is made with 3 lb. fluoride of chrome and 6-1/2 oz. Alizarine Cyanine G G, the dyeing being done as in the last recipe.

Greenish Grey.—A good shade is dyed with 3 lb. fluoride of chrome, 4 oz. Alizarine Bordeaux B, and 4 oz. Diamond Flavine G, working as given in the above recipe.

Grey.—Give a pale blue bottom with an indigo vat, then dye in a bath containing 1 lb. fluoride of chrome, 1/2 oz. Diamine Fast Red F, and 3/4 oz. Anthracene Yellow C; work at the boil for one hour, lift, wash, and dry.

Dark Grey.—A very fine dark grey, almost approaching a black is obtained by the following plan: bottom the wool with a medium blue by means of the indigo vat, dye in a bath containing 1 lb. fluoride of chrome, 3 oz. Diamine Fast Red F, and 3 oz. Anthracene Yellow C.

Slate Grey.—A good slate grey of a slightly greenish tone can be dyed in a bath of 5 lb. acetate of ammonia, 3/4 lb. Acid Blue 4 S, and 1/4 lb. Titan Brown R, working at the boil to shade.

Pale Slate Grey.—The dyeing is done in a bath made with 5 lb. acetate of ammonia, 5 oz. Acid Blue 4 S, and 1-1/2 oz. Titan Brown R, working at the boil for one hour.

Silver Grey.—A very nice shade is dyed with 3 oz. Acid Blue 4 S, 1/4 oz. Titan Red, and 5 oz. acetate of ammonia.

Silver Grey.—A shade similar to the last is dyed in a bath containing 10 lb. Glauber's salt, 5 lb. bisulphate of soda, and 3/4 oz. Anthracite Black R. By adding a little Thiocarmine R the (p. 099) shade can be turned bluer in tone, while the addition of a little Milling Yellow O, or Titan Yellow, turns it to the green side.

Pearl Grey.—Make the dye-bath with 10 lb. Glauber's salt, 5 lb. acetic acid, and 3/4 lb. Naphthylamine Black D. This gives fine shades of pearl grey.

Bluish Grey.—Mordant the wool by boiling in a bath made with 2 lb. bichromate of potash, 1 lb. tartar, and 1 lb. sulphuric acid. Dye in a bath containing 2 oz. Diamine Black (or 3/4 oz. Diamond Black and 1-1/2 oz. Alizarine Cyanine R), working at the boil for an hour and a half.

Grey.—This can be dyed with 3 oz. Nyanza Black B, and 10 lb. Glauber's salt, working at the boil.

Reddish Grey.—A good full shade is dyed with 1-1/2 oz. Cyanole extra, 1/4 oz. Orange extra, 3/4 oz. Archil Substitute N, 10 lb. Glauber's salt and 3 lb. sulphuric acid.

Slate Grey.—The dye-bath is made with 3 oz. Cyanole extra, 1/2 oz. Archil Substitute N, 3/4 oz. Orange extra, 10 lb. Glauber's salt and 2 lb. sulphuric acid.

Bright Pearl Grey.—Prepare a dye-bath with 3/4 oz. Patent Blue, 1/2 oz. Acid Violet N, 3/4 oz. Orange G, 10 lb. Glauber's salt and 2 lb. sulphuric acid.

Stone Grey on Wool.—The dye-bath is made with 1/2 oz. Chromotrop 2 R, 3/4 oz. Cyanole extra, 1-1/2 oz. Fast Acid Blue R, 3/4 oz. Acid Yellow, 20 lb. Glauber's salt, 3 lb. acetic acid. Enter at 80 deg. F., then warm slowly and work to shade, lift, wash and dry.

These recipes will probably be sufficient to show the lines on which greys may be obtained in wool dyeing. It may be added that from the Acid Blacks B, B B, and S, good greys of a violet tone may be obtained, using from 1/2 to 3/4 oz. dye-stuff. The Naphthol Blacks will also be found useful in the same way, while the greys from Anthracene Chrome Blacks and the Alizarine blacks are very good and fast.

Red Shades on Wool.—The number of red shades that may be dyed (p. 100) on wool is infinite. They range over every variety of tint of red, from the palest blush-rose to the deepest crimson, and from the most brilliant pink to the dullest grenat shade.

It is quite impossible here to describe the dyeing of every imaginable shade of red, while the great variety of red dye-stuffs, both natural and artificial, adds to the difficulty of dealing in the space at command with all the various methods and dyes that may be used in the dyeing of reds on wool.

The methods that may be adopted for dyeing red shades on wool are many and various, depending not only on the particular dye-stuff used, but often on the particular shade that is being dyed. One method, which will yield a pale and useful tint with a particular dye-stuff, would fail if a full shade were necessary.

The greater number of red shades are now dyed by means of the artificial dye-stuffs, as these are much easier to dye than are the natural dyes, and they give, on the whole, more even and brilliant shades, while as regards fastness to milling, acids, and light they are fully equal, and in most cases superior, to the natural dyes.

The Direct Red Dyes.—Of this group of red dye-stuffs, Benzopurpurine, Titan Scarlet, Diamine Fast Red F, and Benzo Fast Red are types; many of them have been found to be very serviceable in wool dyeing. They may be dyed either from plain baths containing common salt or Glauber's salt, or from baths containing common salt or Glauber's salt and a little acetic acid.

Alkaline or soap baths do not work well as a rule, and must be avoided in wool dyeing. Generally the dye-bath is exhausted of colour, and full shades are easily obtained, while these reds are in general remarkable for the evenness and uniformity of tint which can be (p. 101) produced. The reds so dyed are, on the whole, fairly fast to soaping, and can be used for dyeing goods that have to be milled, while their resistance to light and air is fairly good. Benzopurpurine and Diamine Red are more or less affected by acids, but the Titan Red and some of the more modern reds, Diamine Brilliant Scarlet, Benzo Fast Scarlets, are all fast to acids. The fastness to washing and light of some of them, Benzo Fast Red, Diamine Fast Red F, Titan Red, is much increased by adding, after the wool has been dyed, 3 per cent. of fluoride of chromium to the dye-bath, and working a little longer.

The dyeing with these colours is done at the boil, and the goods may be entered direct into the boiling bath without fear of uneven shades being produced. This bath may be kept as a standing one, simply adding as each lot is dyed the necessary quantity of dye-stuff, a little fresh water to bring the bath up to its original volume, and a corresponding quantity of the salt originally added. The wool can then be entered and dyed.

In place of using salt or Glauber's salt, acetate of ammonia is an excellent assistant for this class of dyes.

The following are some recipes for dyeing various shades of red on wool with this class of dyes.

Scarlet.—The dye-bath is made with 3 lb. Titan Scarlet C B, and 10 lb. acetate of ammonia. This gives a good bright shade of scarlet, which is fast to acids and soaping, although not fast to light.

Scarlet.—Dye in a bath made with 3 lb. Diamine Scarlet B and 10 lb. Glauber's salt. This yields a light shade, not so fast to acids as the last, but equally fast to soaping and light.

Scarlet.—Make the dye-bath with 3 lb. Benzopurpurine 4 B, and 10 lb. Glauber's salt. This also gives a good shade of Scarlet fast to soaping. It is turned dark blue by acids, and is not fast to (p. 102) light. It is very largely used on underwear goods, but is not so satisfactory for this as the Titan Scarlet C B, or Benzo Fast Scarlet B S.

Scarlet.—The dye-bath may be made with 3 lb. Brilliant Congo G, 10 lb. Glauber's salt and 2 lb. acetate of ammonia. This gives a satisfactory shade of scarlet.

Bright Scarlet.—The dye-bath prepared with 2 lb. Geranine G, 5 lb. sulphate of soda, 5 lb. acetate of ammonia. Work at the boil for one hour, then wash and dry.

Dark Crimson.—Prepare a dye-bath with 1-1/2 lb. Chrysophenine, 1-1/2 lb. Hessian Violet, 25 lb. salt. Heat to 150 deg. F., enter the goods, heat to boil and dye boiling for one hour, take out, rinse and wash.

Scarlet.—A brilliant shade of scarlet can be dyed in a bath of 3 lb. Benzo Fast Red, 1 lb. Chrysophenine, 10 lb. Glauber's salt and 2 lb. acetic acid.

Fast Red.—Dye the wool in a bath boiling, containing 1 lb. Diamine Fast Red F, 10 lb. Glauber's salt, and 2 lb. acetic acid, until the bath is exhausted, then add 3 lb. fluoride of Chrome and work half an hour longer at the boil.

Bordeaux.—Dye with 3 lb. Diamine Bordeaux, and 10 lb. Glauber's salt.

Pink.—Dye with 2 lb. Diamine Rose B D, 10 lb. Glauber's salt and 1 lb. acetic acid.

The basic red dyes are not very numerous, and comprise Magenta, Saffranine, Acridine Reds, Acridine Scarlets, Rhoduline Reds, Rhodamine and Neutral Beds. For successful dyeing they require a perfectly neutral bath. This bath should contain 10 per cent. of Glauber's salt, and is started cold and not too strong; when all the material has been entered the steam may be turned on and the temperature slowly raised, the material being turned over and over. The operation is continued only until the bath has been exhausted of colour, when it is stopped, and the wool taken out, and washed (p. 103) and dried. The liquor in the dye-baths may be allowed to cool down, and then it may be used for making the dye-bath for a second lot of goods, or it may be run away. It is best not to add the dye to the bath all at once, but in several portions as the work proceeds. The affinity of the wool for the basic dyes is usually so strong that if all were added to the dye-bath at the start, then the first portion of the goods entered might take up all, or nearly all, the colour, leaving but little for the last portion; the consequence being that the goods are dyed of an uneven colour, deeper in some parts than others. This defect is remedied by adding the dye in portions, entering the goods rather quickly, working cold, or by adding a little acetic acid and plenty of Glauber's salt. Notwithstanding all these precautions it is quite possible for the shades to come up somewhat uneven. These remarks are applicable not only to the basic reds but to the whole range of basic dyes, hence this class of dye-stuffs is but little used in the dyeing of wool.

Crimson.—Make the dye-bath with 2 lb. Magenta, and 15 lb. Glauber's salt, working as described above. This gives a fine crimson shade which, however, is not fast to soaping or to light. The quantity of dye-stuff given above should not be exceeded or the shades may come up bronzy, this may be avoided if a trace of acetic acid is added to the dye-bath.

Crimson.—Dye with 2-1/2 lb. of Saffranine and 15 lb. Glauber's salt. This dyes a fine Crimson shade.

Deep Red.—Use 3 lb. Rhoduline Red and 10 lb. Glauber's salt.

Scarlet.—The dye-bath is made with 1 lb. Saffranine Prima, 1 lb. Auramine, and 10 lb. Glauber's salt. The goods are entered into the dye-bath at about 120 deg. F., and well worked about, then the temperature is raised slowly. When the dye-bath is exhausted the goods are lifted, washed and dried. There are no pure basic scarlets, and the above and similar combinations of a basic red and a basic yellow are the (p. 104) only ways in which a scarlet can be dyed on wool with basic coal-tar colours.

The basic colours are, in general, the hydrochlorides of some colour base, and in the process of dyeing the acid constituent of the wool fibre unites with the colour base, while the hydrochloric acid which is liberated passes into the dye-bath.

The acid reds are a very large group of red dyes, of somewhat varied chemical composition, which all have the property of dyeing from baths containing Glauber's salt and sulphuric acid or acetic acid, the usual proportions being 10 per cent. of the former, and 2 to 5 per cent. of the acid. Some are best dyed from a bath containing bisulphate of soda. The dyeing should be started cold, or at a lukewarm heat, then steam should be turned on and the temperature raised to the boil, at which it is maintained for an hour; this boiling serving to more intimately fix the dye-stuff on the woollen fibre.

The Eosine reds, of which Eosine in its various brands, Rose Bengale, Phloxine, Saffrosine and Erythrosine, are examples, are best dyed upon wool from a bath containing Glauber's salt and a little acetic acid. They do not require a very acid bath, hence the reason of using acetic acid. The method of dyeing is that given above as for basic reds, namely, enter into cold, or at most lukewarm bath, and raise the heat slowly, continuing the work until the shade required has been obtained. It is a good plan to start work in a neutral bath, and then when the material has become thoroughly impregnated with the dye-liquor to add the acetic acid. The shades obtained from these Eosine reds are remarkable for their brilliance, but unfortunately their fastness to light, washing, etc., is but slight, although it may be increased by treating the dyed wool in a bath of alum or acetate of lead.