1862.] 7 



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 comparatively 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 in the hands of Quintino Sella for crystallometri- 

 cal 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. 



The salt retains a minute quantity of water at 100, but becomes 

 anhydrous at 130. At this temperature it contains 



C 20 H 10 N 3 ,HC1. 



The salt, like most of the rosaniline-salts, is very hygroscopic, a 

 character which must not be lost sight of in the analysis of these 

 compounds. 



The monacid chloride dissolves more readily in moderately strong 

 hydrochloric acid than in water. If this solution, gently warmed, 

 be mixed with very concentrated hydrochloric acid, it solidifies, on 

 cooling, into a network of beautiful brown-red needles, which have 

 to be washed with concentrated hydrochloric acid and dried in vacua 

 over sulphuric acid and lime, since water decomposes them with 

 reproduction of the monacid compound. The salt obtained by the 



