110 Sir Frederick Abel [April 22, 



section of the dye-trade, the wool-dyers (and in some respects it 

 appears to present in this direction a little advantage over the arti- 

 ficial colour ), but the value of its present annual consumption in Great 

 Britain has become reduced from one million to about •10,000/. 

 During the development of the artificial alizarine industry within 

 this third period of six years, the continued researches of Perkin, 

 Schunck, Baeyer, Caro, and others have led to the development of 

 further important varieties of coal-tar dyes, the most valuable of 

 which, discovered by the two last-named chemists, was a beautiful 

 cerise colour, called eosine. 



With the discovery of artificial alizarine the truly scientific era 

 of the coal-tar industry may be said to have commenced, most of the 

 commercially valuable dye-products, obtained since that time, being 

 the result of truly theoretical research by the logical pursuit of 

 definite well understood reactions. The wealth of discovery in this 

 direction made during the last thirteen years is a most tempting 

 subject to pursue, but I am compelled to refrain from entering upon 

 it, further than to point out that the practical significance of beauti- 

 ful scientific researches of many years previous became developed — 

 that one of the results was the production of very permanent and 

 brilliant scarlet and red dyes, the manufacture of which has greatly 

 reduced the market value of cochineal — that the careful study of 

 the original coal-tar colours led to their production in a state of 

 great purity by new and beautifully simple scientific methods (which 

 include the extensive employment as an invaluable practical agent 

 in their production, of the curious gaseous oxychloride of carbon, 

 until lately a chemical curiosity, produced through the agency of 

 light, and hence christened phosgene gas, by its discoverer, John 

 Davy, in 1812) ; and lastly, that even the well-known vegetable 

 colouring matter, indigo, one of the staple products of India, now 

 ranks among the colours synthetically obtained by the systematic 

 pursuit of scientific research, from compounds which trace their origin 

 to coal-tar. 



The rapid development of the coal-tar colour industry has not 

 failed to exercise a very important beneficial influence upon other 

 chemical manufactures ; thus, the distillation of tar, which was a 

 comparatively very crude process, when, at the period of the first 

 Exhibition, benzene, naphtha, dead-oil and pitch were the only 

 products furnished by it, has become a really scientific operation, 

 involving the employment of comparatively complicated but beautiful 

 distilling apparatus for the separation of the numerous products 

 which serve as raw materials for the many distinct families of dyes. 

 Very strong sulphuric acid became an essential chemical agent to 

 the alizarine manufacturer, and, as a consequence, the so-called 

 anhydrous sulphuric acid, the remarkable crystalline body which 

 was for many years prepared only in small quantities from green- 

 vitriol, and of which minute specimens carefully sealed up in glass 

 tubes were preserved as great curiosities in my student's days, is now 



