1887.] on the Work of the Imperial Institute. 109 



ruption since that time by Perkin to our knowledge of organic 

 chemistry have been among the most brilliant and important achieved 

 by chemists of the present day, and have continued to influence in a 

 most important manner the branch of industry which he created. 



The six years succeeding those which formed the first period 

 (1854-1862) of existence of this industry were fruitful, not only of new 

 colours but also of progress made in England, as well as on the Conti- 

 nent, in the development of the manufacture, and of our knowledge 

 of the constitution, of the beautiful dyes which outvie each other in 

 brilliancy. Important researches by Hofmann, which, while establish- 

 iDg the correctness of his scientific conceptions of the real nature of 

 magenta, led to the discovery, by him, of a matchless violet dye, were 

 followed by the production, at the hands of Perkin and Nicholson in 

 England, and of several workers on the Continent, of the well-known 

 gas-light greens, of Bismarck brown, and of some eight or nine other 

 important dyes ; blue, yellow, orange, and scarlet. 



In the next period of six years (1868-1874) another great stride 

 was made in the coal-tar colour industry, due to important scientific 

 researches carried out by two German chemists, Graebe and 

 Liebermann, which led them, in the first place, to obtain an insight 

 into the true nature of the colouring matter of one of the most 

 important staple dye-stufi's, namely the Madder root. They found 

 that this colouring matter which chemists call Alizarine was related 

 to Anthracene, one of the most imporjtant solid hydrocarbons formed 

 in the distillation of coal, a discovery which was speedily followed 

 by the artificial formation of the madder dye, alizarine, from that 

 constituent of coal-tar. At first, this achievement of Graebe and 

 Liebermann was simply of high scientific interest, but Perkin, who 

 was pursuing research in the same direction, soon discovered two 

 methods by which the conversion of anthracene into the madder dye 

 could be accomplished on a large scale, and one of these, which was 

 also arrived at by the German chemists simultaneously wdth Perkin, 

 is still used for the manufacture of alizarine, which was for some time 

 most actively pursued in this country, with very momentous ]-esults, as 

 regards the market value of the madder root. The latter has long been 

 most extensively cultivated in Holland, South Germany, France, Italy, 

 Turkey, and India, the consumption of madder in Great Britain having 

 attained to an annual value of as much as 1,000,000/. sterling. Play- 

 fair pointed out in 1852 that important improvements had been attained 

 in the extraction of the red colour or alizarine from the madder root, 

 the refuse of which, after removal of the dye in the ordinary way, had 

 been made, by a simple treatment, to furnish further quantities of the 

 colouring matter. This result, most valuable at the time of the first 

 great Exhibition, became insignificant when once the dye was arti- 

 ficially manufactured from anthracene ; the price paid for madder in 

 1869 was from 6d. to 8c?. per pound, but now the equivalent in arti- 

 ficial madder dye, or alizarine, of one pound of the root, can be obtained 

 for one-halfpenny. The latter is still used by the most conservative 



