Page:The American Cyclopædia (1879) Volume VI.djvu/347

 DYEING 339 linen and in crimson." Along the coast of Phoenicia they found the two kinds of shellfish called by Pliny the buccinum and purpura, and from them they extracted a juice which caused their name to be ever associated with the rich purple dye. In such estimation was this held in the time of the Roman emperors, that a pound weight of the cloth which had been twice dipped in it was sold, as Pliny states, for a sum equal to about $150. But its use being restricted to the emperors, the art of preparing it was at last lost. It was re- vived in the 17th and 18th centuries in Eng- land and France, but better colors and cheaper processes were then in use. The discoverers and early conquerors of the countries of North and South America were astonished by the skill exhibited by the Peruvians and Mexicans in the application of numerous beautiful dyes extracted from forest trees. According to Pliny, the methods of dyeing black, blue, yel- low, and green were brought into Greece on the return of the expedition of Alexander the Great from India, where it appears that the art of coloring cotton cloths with rich and permanent dyes had long been known and practised. The Venetians and Genoese in the height of their prosperity, in the time of the crusades, transferred the art to Italy ; and Florence in the early part of the 14th century, it is said, contained 200 dyeing establishments. The important dyestuif archil was discovered about the year 1300 by a merchant, of Flor- ence. In the 15th century a work upon dyeing was published in Venice, of which subsequent editions were issued down to 1548, containing full details of the processes employed. From this work it appears that the use of indigo was unknown in Europe at the latter date, though in India it was probably an important article in dyeing at the remotest periods. It was afterward introduced from America together with cochineal, logwood, annotto, quercitron, Brazil wood, and other dyes; but its use in England and Saxony, as of logwood also, met with the most determined opposition. The cultivators of the woad then in use for dye- ing blue caused decrees to be issued against indigo as a most dangerous product. By the German diet in 1577 it was declared to be " a pernicious, deceitful, eating, and corrosive dye ;" and the name was given it of food for the devil. An act of parliament in the reign of Elizabeth forbade its use, and authorized the destruction of it and of logwood wherever found, and this continued in force for nearly a century. About the year 1630 it was dis- covered that the crimson color obtained from cochineal might be converted into a brilliant scarlet by the application of a salt of tin. The introduction of this metal as an occasional substitute for alum as a mordant is attributed to a dyer named Cornelius Drebbel. The use of pure mordants marks the great improve- ment of the art in modern times, as also the introduction of a great variety of new dyes ob- tained from mineral substances. The Flemings during the 17th century carried the skill to which they had attained in this art into Ger- many, France, and England. After them the French directed particular attention to it, and men of eminence in chemical science, as Du Fay, Hellot, Macquer, and Berthollet, were appointed by the government to investigate and perfect the processes. The method prac- tised in the East of giving to cotton the beautiful and permanent Turkey red dye was made known in their publications, and the art was about the same time introduced into France by some Greek dyers. The business was afterward permanently established at Glas- gow by a Frenchman named Papillon. The art of dyeing consists in the application of colors, principally organic, to animal or vegeta- ble fibre or fabrics, such as silk, woollen, linen, or cotton. Some colors possess the property of uniting with the fibre without the intervention of any other body, the coloring matter being immediately taken up and retained in an in- soluble state ; such are called substantive col- ors. Others require the presence of another substance called a mordant, which furnishes a base for the coloring matter to unite with, and which also acts upon the fibre in such a way as to cause the insoluble dye to adhere more closely ; these are called adjective colors. The materials also which are to be dyed have different powers of absorbing and retaining col- oring matters ; wool and silk possessing a great- er facility in this respect than cotton or linen. Wool requires much less preparation than cotton to fit it to receive dyes, either with or without the use of mordants, it being only necessary to cleanse it from a fatty substance called the yolk, which is done by scouring it in a weak alka- line solution. The natural varnish which covers the fibre of silk does not prevent it from ab- sorbing the dye, it being only necessary to rinse it in soap lye at a moderate tempera- ture ; but to remove the varnish boiling in an alkaline solution is usually practised. The dyeing substance must be applied in a state of solution, that the fibres of the material to be dyed may imbibe it. If, however, it remains in the fibre in a soluble state, it does not con- stitute a true dye, this term being only applied to a color which is retained as an insoluble precipitate. A color that may be washed out with warm soap suds or a weak alkaline solution is called a fugitive color ; and one which will resist the action of these agents is called a fast color. Coloring matter may be fixed within a fabric by three methods: 1. By dissolving the dye in some material which being after- ward abstracted will leave it in an insoluble state as regards ordinary solvents, such as soap suds and weak alkaline or acid solutions. If a cloth is stained with a solution of oxide of copper in aqua ammonia, the evaporation of the ammonia will leave the oxide of copper deposited in an insoluble state in and upon the fibre. The deposition in an insoluble condi-