On the Colouring Matters produced from Aniline. 553 



and dissolved in dilute hydrochloric acid, when sulphur, together 

 with impurities, are left behind. The dark-brown solution thus 

 obtained yields, with concentrated hydrochloric acid, a copious cry- 

 stalline precipitate, which, according to the degree of purity of the 

 commercial colouring matter, is either brown or yellow. Washing 

 with concentrated hydrochloric acid, in which the precipitate is in- 

 soluble, effects a considerable purification ; but in most cases it is 

 necessary to repeat the process of dissolving in dilute and reprecipi- 

 tating by concentrated hydrochloric acid once or twice. If the 

 solution, before the last addition of concentrated acid, be heated to 

 ebullition, the liquid remains clear, and the new chloride crystallizes 

 out only on cooling. The crystals are beautiful, white, rectangular 

 plates, which are, however, always very small. Recrystallization from 

 water, in which they are extremely soluble, renders them perfectly 

 pure. Or they may be dissolved in alcohol and precipitated by ether, 

 in which they are quite insoluble. 



The chloride thus purified yields, on addition of ammonia, the 

 leucaniline as a dazzling white powder, which assumes the faintest 

 rosy tint when left for some time in contact with the atmosphere of 

 the laboratory. It is scarcely soluble in cold, very little soluble in 

 boiling water, from which it is deposited, on cooling, in the form of 

 small crystals. It is very soluble in alcohol, and, although less so, 

 in ether. I have not been able to get it in good crystals from these 

 solvents. The best solvent appears to be a solution of the chloride 

 above described, in which leucaniline is freely soluble, and from 

 which, on cooling, it is deposited in the form of interlaced needles, 

 which are frequently united to spherical aggregations. Leucaniline 

 may be dried in vacuo over sulphuric acid without changing its 

 colour. When slightly heated it becomes red, and at 100° it fuses 

 to a deep-red liquid which, on cooling, solidifies to an indistinctly 

 crystalline mass of lighter colour. Leucaniline is anhydrous. The 

 analysis of the substance, dried in vacuo, and at 100°/ has given 

 results which correspond to the formula 



^20 "21 ^*3' 



This formula has been verified by the examination of the chloride 

 already mentioned, of a splendidly crystallized platinum-salt, and, 

 lastly, of the nitrate, which may be likewise obtained in good 

 crystals. 



Hydrochlorate of Leucaniline. — The preparation of this compound 

 has been mentioned. It is triacid, and retains, when dried in vacuo , 

 one equivalent of water, its formula being 



C 20 H 21 N 3 ,3HCl,H 2 O. 



The salt cannot be dried at 100°, at all events in air; but the 

 water may be expelled, although with great difficulty, by exposing 

 the salt for a considerable length of time to 100° in a current of 

 hydrogen. I have endeavoured to convert this compound into a salt 

 with less acid by boiling the solution with an excess of leucaniline, 

 but without result. The boiling solution deposits, on cooling, beauti- 

 ful crystals of the base, the triacid salt remaining in solution. 



Platinum-salt of Leucaniline. — On adding dichloride of platinum 



