COAL-TAR COLORS. Coloring matters arti ficially prepared from coal-tar, chiefly from the hydrocarbons extracted from it. (See COAL TAR.) The first observation of a colored com pound of this class was made by Runge in 1S34; but the real beginning of the great modern color industry dates from 1S5(3, when W. H. Perkins obtained a violet dyestuff by oxidizing impure aniline with chronic acid, took out a patent for it, and commenced manufacturing it in Eng land. Many other dyes were subsequently ob tained from aniline and the substances related to it, by A. W. Hofmann, Gries, Girard, Lauth, and many others. But the most sensational step was the preparation by Graebe and Liebermann (1SOS) of a natural dyestuff—viz. the coloring principle of madder-root. from the anthracene of coal-tar. In 1850 indigo was first prepared, not from coal-tar products, hut by a purely synthetic method. and other natural colors have since been prepared in a similar manner; so that natural dyestuffs reproduced by artificial means need not necessarily originate from coal tar, The artificial indigo and alizarin are not mere substitutes for the natural indigo and madder; they are chemically identical with them, and surpass them in purity, and their adaptability to special methods in dyeing and printing often makes them even more desirable.
But as the cost of manufacture is high, they compete with the natural products on about equal terms. The color industry was first de veloped in England and France, but the more thorough technical instruction at the German universities produced a body of skilled manufac turers and investigators who soon took the lead. At present. in addition to the great factories near Berlin, Frankfurt, Elberfeld, and .i.11ann heim, and a host of smaller ones in various parts of Germany, German capital controls many of the establishments in France, Russia, and other countries. The United States possess few inde pendent factories, and the list of their products is rather limited; indeed, American dyers ap pear to call for a smaller range of dyestuffs than those of other countries. A peculiar de velopment of the last fifteen years is the exten sion of the methods of the dye industry to the production of artificial drugs, such as antipyrin, antifebrin, etc.. many of which are manufactured in the same establishments which control the dye patents.