8 



Dr. Hofmann on Aniline-yellow, 



[Nov. 19, 



Under conditions not yet sufficiently defined, this substance is precipitated 

 with water of crystallization as 



C,,H,,N3, 2HC1 + H,0. 



For analysis these salts were dried at 100° or 120°, at which temperature 

 they remain quite unchanged. When heated more strongly they lose 

 hydrochloric acid. "When the diacid chloride is maintained for a fortnight 

 between 160° and 180°, the weight of the salt again becomes constant. 

 The residuary yellow crystalline powder, differing from the original hydro- 

 chlorate only by its somewhat diminished solubility in water, was by ana- 

 lysis found to be the pure monacid hydrochlorate of chrysanihne, 



C,,H„N3, HCl. 



The crystalline compounds which chrysaniline forms with hydrobromic 

 acid and hydriodic acid are perfectly analogous to the salts produced bj^ 

 hydrochloric acid. I have not analyzed them. 



The nitrates of chrysaniline are the finest salts of this base ; these 

 compounds crystallize with the utmost facility in ruby-red needles, which 

 are remarkably insoluble in water. A dilute solution of nitric acid (1 grm. 

 of HNOg in a litre of water), when mixed with moderately dilute solutions 

 of the chloride, yields immediately a crystalline precipitate, so that soluble 

 chrysaniline salts might be used as a test for nitric acid. For the same 

 reason nitric acid is conveniently employed in separating chrysaniline from 

 the crude liquid obtained by boiling out the secondary products of the 

 manufacture of rosaniline. Nevertheless the preparation of the nitrates 

 presents unusual difficulties, and I have lost much time in endeavouring 

 to fix the conditions under which the monacid and the diacid salts may be 

 separately produced. On boiling an excess of free chrysaniline with dilute 

 nitric acid, a solution is obtained depositing, on cooling, needles which are 

 the mononitrate, 



C,,H„N3,HN03, 



in a state approaching purity. On pouring the solution of this salt into 

 cold concentrated nitric acid, a salt is at once precipitated which crystallizes 

 in ruby-red prisms very similar to ferricyanide of potassium, and con- 

 stitutes the nearly pure dinitrate, 



C,„H„N3(HN03),. 

 But here also analysis^ exhibits slight discrepancies, indicating the presence 

 of traces of the former compound. By treatment with water the dinitrate 

 gradually loses its nitric acid, and after two or three crystallizations it is 

 converted into the mononitrate. 



The sulphate is very soluble, scarcely crystalline. 



The platinum-salt is a splendid scarlet crystalline precipitate, which, 

 from hot and rather dilute solutions containing much free hydrochloric 

 acid, is often deposited in very fine and large plates. All my attempts to 

 obtain this substance in a state of purity have failed. The platinum per- 

 centages vary with every new preparation, indicating the formation of a 



