1864.] 



derived from Coal-tar. 



489 



blue mass produced to destructive distillation over a naked burner. The 

 distillate is treated with hydrochloric acid, and subsequently vi'iih. water, 

 when aniline and toluidine, together with several other basic substances 

 accompanying the phenyltolylamine, remain as hydrochlorates in solution. 

 The oily layer which separates generally solidifies, or may be purified by 

 rectification. The resulting crystals are crystallized from alcohol. 



The same method is also adapted for the preparation of diphenylamine, 

 aniline being substituted for toluidine. 



If I have bestowed upon diphenylamine and phenyltolylamine rather 

 more attention than these substances at the first glance appear to claim, I 

 have done so in the hope of gaining additional data for the investigation of 

 the remarkable colouring matters from which these bases are derived. 

 Both constitution and mode of formation of these colouring matters are 

 still involved in darkness. Theory, as it often happens, has not kept pace 

 with practice. The anticipation I expressed in a former note, that the 

 study of the behaviour of the colouring matters under the influence of 

 chemical agents might disclose their true nature, has only very partially 

 been realized. Up to the present moment, chemists have not succeeded in 

 giving a satisfactory account either of the atomic construction of these 

 compounds, or of the mechanism of their formation ; and it would there- 

 fore scarcely be worth while to return to this question before its definite 

 solution, unless the publication of erroneous statements by M. Schiff had 

 threatened to divert the researches of chemists from this subject. 



According to M. Schiff*, the transformation of aniline into aniline-red by 

 means of stannic chloride is represented by the equation 



20Ce H, N + 1 Sn CI, = 3(ao H^^ N3, HCl) + 6(Ce H, N, HCl) + 

 H, NC1+ 10 Sn Cl + 4 Ce H.N. 



The formation by means of mercuric nitrate f by the equation 



2OC3 H,N + 20 HgN03=3(C,o H„ N3, HN03) + 6(Cg H, N, HN03) + 

 H, N, NO3 + 1 OHg^ NO3 + 4Ce H, N. 



The latter process is accomplished at as low a temperature as 80° C, 

 and, according to M. Schiff, is so elegant that he was enabled to make 

 quantitative experiments. Within a few hundredths," he says, "we 

 have obtained the requisite quantities of the sought-for materials." 



M. Schiff' s equations are not conspicuous for elegance and simplicity, 

 but they are absolutely inadmissible for other reasons. These equations 

 utterly ignore the very essence of the process. I have pointed out, some 

 time ago, that the formation of rosaniline involves the presence of both 

 aniline and toluidine. Pure aniline furnishes no rosaniline, nor can this 

 body be procured from pure toluidine. This fact I have since further 

 established by many varied experiments, both on the small and on the 

 large scale. The formation of rosaniline thus becomes the means of 

 ascertaining rapidly the presence of toluidine. The amount of the latter 



* Compt. Rend. vol. Ivi. p. 271. t Ibid. p. 545. 



VOL. XIII. 2 o 



