550 Royal Society : — 



The combustion of rosaniline has led to the formula 

 C 20 H 21 N 3 O = C 2 JI 19 N 3 ,H 2 O, 



which has been corroborated by the examination of numerous well- 

 characterized salts and derivatives. 



Rosaniline is a well-defined powerful base, which forms several 

 series of salts, nearly all remarkable for the facility and beauty with 

 which they crystallize. The proportions in which this substance 

 unites with acids characterize it as a triacid triamine. Like several 

 other triamines which I have examined, it will probably be found to 

 produce three classes of salts, viz., 



C 20 H 19 N 3 , HC1, 

 C O0 H 19 N 3 , 2HC1, and 

 C; o H 19 N 3 , 3HC1. 



Up to the present moment, however, I have been able to obtain only 

 representatives of the first and the third of these classes. The predilec- 

 tions of rosaniline are essentially monacid. The salts with one equiva- 

 lent of acid are wonderfully stable compounds. I have recrystallized 

 them four and five times without producing the slightest alteration in 

 their composition. The salts with three equivalents of acid present 

 comparatively little stability, being, in fact, decomposed by the action 

 of water or by exposure to 100°. 



By a glance at the formula given, it is obvious that the white cry- 

 stals of the base itself, which were submitted to examination, are a 

 hydrate, — the saline compounds of rosaniline, as might have been 

 expected from many of the processes of their formation, containing 

 no oxygen. The salts of rosaniline may be obtained by two differ- 

 ent processes : either by the direct action of the respective acids, or 

 by submitting the ammonium-compounds of the several acids to 

 ebullition with an excess of the free base. Both processes yield the 

 salts equally pure and of exactly the same composition. The salts 

 with one equivalent of acid exhibit for the most part, in reflected 

 light, the splendid metal-lustrous green of the wings of the rose- 

 beetle ; in transmitted light the crystals are red, becoming opaque 

 when they acquire certain dimensions. The solutions of these salts in 

 water or alcohol possess the magnificent crimson colour for which 

 rosaniline has become so justly celebrated. The salts with three 

 equivalents of acid, on the other hand, are yellowish brown, both in the 

 solid state and in solution. They are much more soluble in water and 

 alcohol than the monacid salts, which for the most part are compara- 

 tively sparingly soluble. Both classes of rosaniline-salts crystallize 

 readily, more especially the monacid compounds ; some of them Mr. 

 Nicholson has obtained in perfectly well-formed crystals, which are at 

 present inthehands of Quintino Sella for crystallometrical examination. 

 Chlorides. — These substances, and more especially the monacid 

 salt, were of particular use in fixing the formula of rosaniline. Pre- 

 pared either by the action of hydrochloric acid, or by means of chlo- 

 ride of ammonium, the salt is deposited from the boiling solution in 

 well-defined rhombic plates, frequently united in stellar forms. The 

 chloride is difficultly soluble in water, more soluble in alcohol, 

 insoluble in ether. 



