246 SCIENCE PROGRESS 



the industry considerably, in Great Britain the manufacture 

 of synthetic dyes was in a state of vigorous and sustained 

 development, and it is therefore hardly surprising that many 

 German chemists came over to this country either to study 

 under Professor Hofmann, or to take up a technical position. 



In particular two names must be mentioned : Heinrich Caro, 

 who for some years was engaged at the dye-works of Dale, 

 Roberts & Co., of Manchester, and Peter Griess, who was 

 chemist at the brewery of Messrs. Allsopp & Co., and devoted 

 his spare time to research work which was later almost to 

 revolutionise the dye industry. 



During the period i860 to 1865, therefore, Great Britain 

 was the centre par excellence of the dye industry, with Hofmann 

 working chiefly at the purely scientific side of the matter in 

 London, and Caro, Griess, Schunck, and many others at work 

 on the technical side in Manchester. In 1862 Nicholson, also 

 one of Hofmann's pupils, prepared the " soluble blue " named 

 after him ; Caro, in the attempt to produce mauve by direct 

 oxidation on the fibre, obtained instead aniline black, and 

 shortly after he prepared induline and nigrosine for the first 

 time, which are still used in some quantity for the manufacture 

 of printing inks. 



In 1863 Roberts, Dale & Co., no doubt with the advice of 

 Caro, whom they had persuaded to become a partner in i860, 

 obtained the services of Dr. Martius, and his first-fruit of 

 discovery in Manchester was the brown dye known as Bis- 

 marck- or Manchester-brown, by the action of nitrous acid 

 on metaphenylenediamine, and in the following year Martius 

 yellow or Manchester yellow made its d£but, having been made 

 simultaneously by Caro and Martius, so that already well over 

 a dozen new dyes were being prepared on a large scale by this 

 date ; and at the International Exhibition of 1 862 three English 

 firms — Perkin & Sons ; Roberts, Dale & Co. ; and Simpson, 

 Maule & Nicholson — were exhibiting, besides the French firm 

 of Renard Freres and the German firm of Frank. Hofmann 

 was studying the constitution of rosaniline and " Bleu de Lyons ' 

 meanwhile in London, the latter of which he showed to be a 

 phenylated rosaniline, and arising out of this discovery he 

 succeeded in preparing the so-called " Hofmann's violet ' 

 already mentioned, leading soon after to the various shades of 

 methyl violet which still form an important item in the dyer's 



