That dyeing was practised in the most ancient times is abundantly proved by the frequent mention of dyed colours in the oldest extant writings; that it was not a common art seems apparent from the uses to which coloured garments were devoted, and the distinction which they conferred upon the wearers. It is probable that such definite and bright colours as the “blue, and purple, and scarlet” mentioned several times in the book of Exodus, as well as the Tyrian purple so often referred to by Roman writers of the Augustan age, were so costly as not to be available for general and common use. Pliny is the only one of the older writers from whom we might have expected some account of the processes of dyeing employed at his time; but, except a reference to two or three tinctorial substances, and a description of a process of obtaining several colours by one dyeing operation, which he saw practised in Egypt (see Calico-Printing, vol. iv. p. 684), there is nothing detailed in his writings;—he in fact formally excuses himself from entering upon the subject as one not worthy of his attention. The Tyrian purple is the only dye treated of at some length in Pliny and contemporary authors; its discovery and employment gave wealth and prosperity to Tyre and Sidon more than 1000 years b.c. In the days of the Roman conquests in the East it was reserved under penal statutes for imperial use; its production then declined, and eventually both the material and the art of using it were lost. From Pliny’s description, modern investigators were enabled to rediscover the shell-fish which yielded the dye, but the colours furnished by it were neither so bright nor so permanent as those obtainable from much less costly dyeing materials; and there is reason to conclude that the most brilliantly tinted garments of an Egyptian priest of Isis or Osiris, or the mantle of a Roman emperor, were poor and dull in hue compared with those within reach of a domestic servant of the present time.

From many independent sources — Homer, Strabo, Herodotus, &c.,—it is clearly shown that the manufacture of coloured tissues was carried on by the Oriental nations. A knowledge of the art spread slowly westward, but there are few records of its existence to be found from the time of Pliny to about the 13th century. It would appear that the Jews held the secret or the monopoly of the dyeing art during this long period. According to Mrs Merrifield, Benjamin of Tudela relates that when he visited Jerusalem between 1160 and 1173 he found only 200 Jews resident in that city, and these were all engaged in wool-dyeing, which trade was entirely in their hands. Beckmann shows that at the same epoch the art of dyeing in Italy was principally carried on by Israelites. It is in Sicily that we can first distinctly discern the practice of dyeing in Europe; afterwards the Italians generally practised it; and in the 13th century dyers formed important guilds in Florence, Venice, and other cities. It is not to be supposed that the art of dyeing was ever completely lost; the records of particular seats of the art only indicate that at such places some special excellence had been acquired which gave them a higher reputation than was enjoyed by others. The domestic records of all modem nations speak of dyers and dyed cloths. Among the ancient laws of Ireland are some which lay down the number of colours that may be employed in the dress of various classes of society, the monarch alone being permitted to wear seven colours; from which it may be inferred that if the Irish at a very early period were not dyers, they at least had variously dyed gaπnents. Similar facts can be adduced of all countries that possess an early literature.

From the perishable nature of textile substances and their comparatively small intrinsic value, very few ancient examples of the dyer’s art have been preserved. We have, however, one account of a cloth containing dyed yarn which may have been in the dyer’s hands in Egypt 1000 years before the Christian era; and we have still in good preservation ecclesiastical vestments containing dyed silks which are certainly 600 to 700 years old. The late Mr Thomson of Clitheroe examined numerous mummy cloths, some of which had a border of blue and fawn-colour made by coloured threads introduced into the loom. The blue, upon examination, was proved to have been dyed with indigo; other specimens of mummy cloth of a reddish colour appeared to have been dyed with safflower, though this colouring matter could not be recognized with the same certainty as indigo. Dr Rock, in his catalogue of the textile fabrics in the South Kensington Museum, attributes many of the church vestments there preserved to the 12 th and 13th centuries, and in these can be seen silks of all the colours known to dyers up to the middle of the present century, which, though in most cases changed and faded, still present sufficient evidence that dyeing, upon this material at least, was successfully practised in the Middle Ages. It is interesting further to note that in inventories of vestments of the 13th century the silks in the vestments are often designated by their colours, as in a chasuble at St Paul’s, London, 1295, which is set down as “purpureo aliquantulum sanguineo,” of a purple inclining to blood red. This, as Dr Rock says, is intelligible; but other definitions are not, as “pannus Tarsici coloris,” a Tarsuscoloured cloth; it can only be conjectured that it was a purple dyed at Tarsus, and something like the Tyrian purple; sky-blue silk is named “indicus,” probably because it was dyed with indigo.

The earliest account of the processes and materials used by dyers is to be found in a collection of manuscripts in the French National Library, No 6741, known as the manuscripts of Jehan le Begne. These mostly refer to the art of painting and the making of artists’ colours and the modes of applying them, but some describe the preparation and use of dyes. The most interesting of these manuscripts is by Jehan Alcherius (Le Begne was only the copier or compiler), which from internal evidence cannot be dated later than the year 1410, and some parts of which refer to a period at least thirty years earlier. Among the colouring matters and mordants there mentioned we find iron (the dust or mud from grindstones on which knives are ground) dissolved in vinegar and mixed with alum, green copperas, and gall nuts prescribed as a black colour; and methods are given for the use of Brazil wood, litmus, indigo, in conjunction with lime and honey, verdigris, alkalies, oxide of tin, kermes, <fcc., much in the same way as those employed four centuries later by dyers and calico-printers. There are also eleven receipts for preparing colours, for painting on cloth to imitate tapestry,—examples of which (toiles peintes) of the 15th century were exhibited in Paris in 1876. Curiously enough, a certain Fleming named Theodore in 1410 brought these receipts to Alcherius from London, where they were in regular use. They are all chemical dyes, and seem to be the prototypes of the same class of colours employed long subsequently by calico-printers in England and other countries.

The first printed account of dyeing processes was an Italian work. It is referred to under the title Mariegola dele arte dei Tiηtοri, published at Venice in 1429. The writer has never seen a copy of this work, nor does it appear that any exists in the chief libraries of Europe; an enlarged edition was published in 1510. In 1548 Rosetti wrote an account of dyeing, which was also published at Venice. Copies of this are not veιy scarce; it is the only one of these early books which is actually known. The so-called Bolognese manuscript translated in Merrifield’s Ancient Practice of Painting, is preserved in the convent of St Salvatore at Bologna, and is said not to be of later date than the middle of the 15th century—that is, about 100 years anterior to the date of Rosetti’s work. In this manuscript, in addition to the materials enumerated by Alcherius, mention is made of woad and methods of making indigo from it; of indigo imported from India, called bagadon and bagadd; of sumach, gall nuts, and lac; of the berries of buckthorn, similar to the Avignon or Persian berries, to be used for yellow; and of Brazil wood or verzino, sandal wood, and madder for red; and archil for purple. The use of nitric acid to give a yellow colour to silk, and of alum for preparing and mordanting that material, and the subsequent dyeing of it by Brazil wood, are also clearly pointed out. The receipt No. 362 of this manuscript is of interest as showing that the Italian dyers early possessed the method of dissolving indigo by means of the action of honey and quick lime upon it, and used the solution for the blue required in dyeing silk green.

It is very clear, then, from these accounts, and from numerous existing samples of coloured stuffs, that dyeing was well understood in Europe in the 15th century, and that the materials at the command of the dyer were sufficiently numerous and varied to enable him to produce all desired shades of colour. The improvements which took place in the dyeing art from this time until the commencement of the present era of artificial colouring matters were no doubt important in detail, but not very striking in principle.

The discovery of America was soon followed by the introduction of cochineal (see vol. vi. p. 97), but this did not enable the dyer to produce any new colours, since it differed from the ancient kermes, frequently called grana or grains, only in being ten or twelve times as rich in colouring matter. Logwood or Campeachy was also an introduction from the New World, and greatly enlarged the power of the dyer, though, from the looseness of the colours it yielded, it brought his art into some disrepute; it was in many respects a new colouring matter, but eventually settled down as the principal ingredient in the common black dye. In mordants, the discovery in Holland in the 17th century of the use of solutions of tin in acid, especially for the scarlet dye with cochineal, was one of the greatest utility. The gradual introduction of the acetates of alumiuium and iron to replace the respective sulphates was of more importance > calico-printing than dyeing proper. At the close of the last century Dr Bancroft discovered and introduced quercitron bark from America for dyeing yellows, and this, from its superior richness and less cost, displaced other materials used for that purpose. Of the natural dyes introduced in the present century probably the most important is catechu. The discovery of the use of bichromate of potash as a mordant for woollen goods belongs to the latter half of this century, and has been of the highest benefit to the dyer. We shall not speak in detail of a number of dyestuffs used by dyers of the present day, which were probably unknown to their predecessors, because most of them are only varieties of what have been long employed. Such, for example, are valonia, divi-divi, and myrobalans, which have no properties different from galls or sumach, and the different red woods, which are merely varieties of the anciently known Brazil woods.

Artificial Colouring Matters.— In the year 1858 commenced the discovery and application of a series of artificial colouring matters, which have created a distinct era in the history of dyeing. Up to that date the colouring matters used in dyeing were either the spontaneous productions of nature or simple preparations of the same. An exception, however, must be made to this statement in respect of Prussian blue and the so-called sulυhate of indigo, which have been largely used as colours in dyeing since the middle of the last century, and are as truly products of art as any of the modern creations of chemistry. The purple of murexide had only a brief existence as a dye. Mr Perkin was the first to practically produce a dyeing material from aniline, the well-known mauve or purple shade so much in vogue for several years, for a history of which see vol. ii. p. 48 of the present work. Other discoveries rapidly followed, and in the course of a few years it may be said that a hundred patents were taken out for methods of making artificial colouring matters from aniline and its homologues; these alkaloid bases, under the transforming hands of chemists, supplied the dyer with every shade and hue which could be desired. Up to 1869 the artificial colours were of one general family, and had many characters in common; they were very brilliant, very easily applied on fibre of animal origin (silk and wool), required no mordant, and for the most part were very loose and unstable. Imitating more or less closely the colours obtained on tissues from natural colouring matters, they had no similarity of chemical composition, and were in every other respect fundamentally different from them. In 1868 two German chemists, Graebe and Liebermann, by means of a severe synthetical investigation, succeeded in transforming anthracene into alizarin, the latter ’being identical in chemical composition as well as tinctorial properties with the colouring matter of madder, one of the most anciently known and most valuable of all natural dye-stuffs (see vol. i. p. 577). This was the first instance in which chemistry had produced one of the old and well-known colours of the dyer; in a short time after its discovery it was made practically available for the trade, and has at this date (1877) almost entirely driven from the market the native product,— accomplishing a revolution which has no parallel in the history of colouring matters, and which is one of the most signal triumphs of modern chemistry. Other natural colouring matters have since then been produced by art, such as indigo and archil, but from some difficulties in their manufacture they have not yet become commercially available.

Mechanical Improvements.— In the art of dyeing, steam power has proved no less serviceable than in other important industries. Its applications are not further alluded to in this article, but in the article upon Calico-Printing (vol. iv. p. 684) some illustrations of modern machinery may be seen.

General Principles of Dyeing.

Although many eminent chemists have worked and written upon the subject, there still remains much difference of opinion as to - what actually takes place in dyeing operations. The following general account of the chief cases of dyeing will illustrate the principal methods in use, and serve as an introduction to a description of’actual processes practised in dye-houses. Afterwards, the attempts made to construct a general theory will be briefly considered. The simplest cases of dyeing are those in which only two substances are employed—the fibre to be dyed and the colouring matter—and where the process of dyeing consists in nothing more than leaving the two materials in contact for a certain time at a convenient temperature. Of natural colouring matters few can be practically used in this simple way without some previous chemical treatment. The artificial colouring matters from aniline, however, illustrate this kind of dyeing very well. To obtain the finest shades of mauve, magenta, purple, and numerous other colours upon wool and silk fibre the whole process consists in placing the material in a solution of the requisite colour and of sufficient quantity to give the desired shade; it absorbs the colour, becoming dyed, while the solution is rendered nearly colourless. During the process the fibrous material is kept in a constant state of movement, so that the dye solution shall have equal access to all portions, the temperature employed and time allowed being regulated according to the necessities of the case. The colour absorbed by the fibre has entered into an intimate state of combination with it, since it cannot be washed out again; a true dyeing has taken place. Besides the aniline colours, the older artificial dyes—sulphindigotic acid, picric acid, and one or two others—have the same property of combining directly with wool and silk.

There are other cases of dyeing closely resembling the foregoing, in which the resulting dyed stuff may be considered as being a binary compound of fibre and colouring matter, but in which the methods of application are less simple. These may be taken generally as consisting in the use of materials or processes which bring a previously insoluble colouring matter into a soluble state; thus the pink colours of safflower are obtained by the action of an alkali; and the dyes yielded by archil, arnotto, and indigo are also the result of the action of solvents. It is possible that during the process of solution important internal changes may take place in the composition of the above dyes, but if so, they are only of a temporary nature, for there is no reason to suppose that the colouring matter attached to the fibre differs in chemical composition from that which is free.

With regard to nearly all other colouring matters, the above simple processes are quite powerless to induce a permanent combination with the fibre. Let wool or silk be immersed at boiling temperature in decoctions of any of the best known natural dye-stuffs, such as cochineal, logwood, madder, quercitron bark, <fcc∙, and then washed in water, it will be found that the fibres are simply discoloured, or stained of no definite shade; they have taken up but a small portion of colour from the decoction, and no real dyeing has taken place.

Use of Mordants.— To obtain permanent dyes from the great majority of native colouring materials the intervention of another class of bodies entirely different from either fibrous or colouring matter is found necessary; these bodies are called mordants. The term mordant is found in Latin and Italian manuscripts of the 12 th and 13th century, as the name of an adhesive composition by means of which gold leaf could be attached to wood, marble, or metal; early dyers appropriated the word to designate a substance by means of which colouring matters could be made to adhere to fibre, and it has been retained in that sense in all modem treatises upon dyeing.

The chief mordants used in dyeing are salts of aluminium, iron, tin, chromium, copper, and a few other metals. When a decoction of a colouring matter, say logwood or cochineal, is heated with a small quantity of a properly chosen salt of one of these metals, it is found that the colouring principle loses its solubility, forms a combination with the metallic salt or its bases, and precipitates to the bottom of the solution, leaving the supernatant liquid nearly or quite colourless. The precipitate is usually called the “lake” of the particular metal and colouring matter, which are probably in a state of chemical combination; the lakes are insoluble in water, and are only split up again into their constituents by the action of somewhat powerful chemical agents.

Fibre cannot usually be dyed by means of ready formed lakes, for the reason that they are insoluble in water and not easily soluble in any menstruum which can be safely applied to such material; they are themselves of too coarse and gross a nature to penetrate the fibre, and when applied to it rest for the most part on the surface, and are therefore easily removable by washing or mechanical friction. It is known, however, that for...