September 6, 1895.] 



SCIENCE. 



289 



termined tile composition of the lighter oils 

 in the market and found that they con- 

 tained a considerable quantity of benzene, a 

 fact discovered by Hoffmann two years be- 

 fore. Supplies for the subsequent uses in 

 the color industry were therefore possible. 



It may be observed here that the dis- 

 covery of this compound by the dry distilla- 

 tion of coal, de novo, in the laboratory, would 

 have been practically impossible* since, ac- 

 cording to Perkin,t 100 lbs. of coal yields 

 only 0.85 oz. of coal tar naphtha, and 0.275 

 oz. of benzene. The operations of the in- 

 dustry carried out on a large scale are neces- 

 sary to this, I and such operations we know 

 and shall see have furnished to those work- 

 ing in purely scientific lines materials for 

 study which has given the most important 

 results and without which many of the re- 

 lations would still be unknown. 



But to proceed. With the commercial 

 production of benzene, its derivative nitro- 

 benzene was readily obtained in large quan- 

 tities. It had been made, it is true, years 

 before by Mitscherlich in 1834, from benzene 

 of benzoic acid, and by Laurent a little 

 later by the action of nitric acid upon light 

 oil of tar. Collas, a French pharmacist, 

 made it in 1848 in a large way in Paris and 

 later Mansfield took up its manufacture 

 from the product of his stills, putting it on 

 the market as artificial oil of bitter almonds, 

 or oil of Mirbane, to be used in scenting 

 soap. 



So aniline which Unverdorben produced 

 in 1826 by dry distillation of indigo and 

 called krystallin, and Runge first separated 

 from coal tar by treating it with hydro- 

 chloric acid in 1834 and called blauol, and 

 Fritsche produced by digestion of indigo 

 with potash and distillation of the product 

 in 1840 and called anilin, and Zinin pro- 



. ' * Compare Sosooe and Schorlemmer, Treatise on 

 Chemistry, III., pt. iii., 15. 



t Jonr. Soo. Arts. 1869. 101. 



t Compare Hoffmann. Jour. Soc. Arts, 1863. 647. 



duced in 1842 by reduction of nitrobenzene 

 with ammonium sulphide and called benzi- 

 dam, remained a scientific curiosity the true 

 constitution of which was not fully deter- 

 mined until some years after it had been pro- 

 duced by Bechamp by reduction of coal tar 

 nitrobenzene with iron and acetic acid and 

 Perkin had utilized it in the manufacture 

 of mauve. 



And so the way for Perkin had been pre- 

 pared. Both the industry and the science, 

 so far as they had been able, had done their 

 share: the industry, by efforts at the utili- 

 zation of the products at hand and showing 

 possible commercial profit; the science, in 

 the struggle after new compounds. The 

 spirit of the iatro-chemists still prevailed 

 and substantial benefits flowed from it as of 

 old. Perkin,* likewise in an effort to pro- 

 duce a compound valuable and scarce in the 

 market and to effect the synthesis of qui- 

 nine, produced aniline purple or mauve in- 

 stead. Starting out, as he says, with the 

 consideration of the empirical formula, he 

 concluded that by the oxidation of allyl-to- 

 luidine he might attain his end. Describ- 

 ing his expei'iment, he says: " For this pur- 

 pose I mixed the neutral sulphate allyl-to- 

 luidine with bichromate of potassium, but 

 instead of quinine I obtained only a reddish 

 brown precipitate. ISTevertheless, being 

 anxious to know more about this curious 

 reaction, I proceeded to examine a more 

 simple body under similar circumstances. 

 For this purpose I treated the sulphate of 

 aniline with bichromate of potassium. The 

 mixture produced nothing but an unprom- 

 ■ ising black precipitate; but, on investiga- 

 ting this precipitate, I found it to be the 

 substance which is now, I may say, a com- 

 mercial necessity." Perkin treated the 

 black precipitate with different solvents in 

 the study of its properties and found it to 

 yield to alcohol a colored solution. With 

 more of the inventive and commercial spii'it 

 *Chemical News, 1861. 347. 



