1863.] 



Dr. Hofmann on Aniline-blue, 



13 



confers such value upon these substances as agents of research. "We are 

 unable to substitute phenyl for hydrogen by processes borrowed from the 

 experience gathered in experimenting with the ordinary alcohols. Diphe- 

 nylamine and triphenylamine are substances existing at present only in the 

 conception of the chemist. It was reserved for the peculiar, I might 

 almost say instinctive mode of experimenting belonging to industry to fill 

 up this blank. 



The transformation of rosaniline into aniline-blue suggests some other 

 questions which must not altogether remain unnoticed here, although I 

 hope to enter more fully into this subject elsewhere. Does this trans- 

 formation simply involve an interchange between the hydrogen and phenyl 

 atoms, or does the rosaniline molecule lose ammonia, which is replaced by 

 aniline ? 



I do not pretend to answer this question ; but I beg leave to record some 

 experiments as materials towards the solution of the problem. 



Methylicy EthyliCj and Amylic Derivatives of Rosaniline. 

 The interpretation of the results delineated in the previous pages legiti- 

 mately suggested the study of the behaviour of rosaniline under ordinary 

 processes of substitution — in other words, the treatment of this base with 

 the iodides of methyl, ethyl, and amyl. I will not describe the pleasure 

 with which I observed the intense blue colour of the mixture of rosaniline 

 with these iodides when, after a day's digestion, I took the sealed glass 

 tubes from the boiler. The action of iodide of methyl and ethyl is readily 

 accomplished at 100° C; iodide of amyl requires a temperature of from 

 150° to 160°. The presence of alcohol facilitates the reaction. 



Up to the present moment I have only examined in detail the action 

 of iodide of ethyl. The product of this action is an iodide which dissolves 

 with a magnificent blue colour in alcohol. The tinctorial powers of this 

 solution are scarcely inferior to that of rosaniline itself ; and industry will 

 probably not disdain to utihze this latest indication of science. 



The blue ethylated derivative of rosanihne, as might have been ex- 

 pected, presents in its properties greater analogies with rosanihne itself 

 than the triphenylic compound. This analogy suggested difficulties in the 

 separation of the two substances which it appeared better to avoid. The 

 iodide produced by the reaction was therefore at once decomposed by soda, 

 and the ethylic derivative, together with the unaltered rosaniline, again 

 submitted to the action of iodide of ethyl. After this process had been 

 once more repeated, the alcoholic solution of the final product was preci- 

 pitated by water, which separated a soft resin-like substance, soHdifying 

 on coohng with crystalline structure, and exhibiting a very peculiar 

 metaUic lustre intermediate between those presented by the salts of ros- 

 aniline and of its phenylic derivative. Crystallization from dilute spirit 

 furnished the iodide in the pure state. The results obtained in the com- 

 bustion and iodine determination of this substance agree with the formula 

 C,3 H3, N3 I = C,o 11,0 (C, H,)3 N3 C, 1, 



