18630 



Dr. Hofmanu on Aniline-yellow, 



7, 



and 1. therefore beg leave to submit to the Royal Society the results of 

 these researches as they present themselves. These Notes must neces- 

 sarily be of a somewhat fragmentary character ; but I hope to collect 

 the results thus gradually accumulating, and to lay them before the Royal 

 Society in more logical order and a more elaborated form. I begin the 

 account of this series of experiments with the description of a yellow 

 colouring matter which is obtained as a secondary product in the manu- 

 facture of rosaniline. 



Chrysaniline. — It is well known that even in the most successful opera- 

 tion, and whatever the process of preparation may be, the rosaniline pro- 

 duced is only a small percentage of the aniline employed. Together with 

 the crimson-colour a large proportion of a resinous substance of feebly 

 basic properties is formed, the generally ill-defined characters of which 

 have hitherto baffled all attempts at a thorough investigation. This mix- 

 ture contains nevertheless several individual compounds, which may be 

 extracted with boiling water, and subsequently separated by treatment 

 with reagents. Mr. E. C. Nicholson has thus isolated a magnificent 

 yellow colouring matter. Considerable quantities of this interesting body, 

 Mr. Nicholson with his usual liberality has placed at my disposal, for 

 which my best thanks are due to him. 



The yellow colouring matter, for which, on account of the splendid 

 golden-yellow tint it imparts to wool and silk, and in order to record its 

 origin, I propose the name of chrysaniline, presents itself in the form of a 

 finely divided yellow powder, closely resembling freshly precipitated chro- 

 mate of lead, perfectly uncrystalline, scarcely soluble in water, which it just 

 colours, easily soluble in alcohol and in ether. This compound is a well- 

 defined organic base, which forms with the acids two series of crystallized 

 sahne compounds. The most characteristic salts of chrysaniline are the 

 nitrates, more especially the mononitrate, which is difficultly soluble in 

 water, and crystallizes with facility. It was from this compound, purified 

 by half a dozen crystallizations, that I prepared the chrysaniline for 

 analysis. An aqueous solution of the pure nitrate decomposed with am- 

 monia yields the chrysaniline in a state of perfect purity. The analysis of 

 this substance, dried at 100°, has furnished results which may be trans- 

 lated into the formula 



This expression is corroborated by the examinatioi»of several salts, more 

 especially the beautiful compound which this base produces with hydro- 

 chloric acid. 



Hydrochlorate of Chrysaniline. — On adding concentrated hydrochloric 

 acid to a solution of chrysaniline in the dilute acid, a scarlet crystalline 

 precipitate is produced, consisting of minute scales very soluble in water, 

 less soluble in alcohol, almost insoluble in ether. These crystals con- 

 stitute the diacid chloride of chrysaniline, 



C,,H,,N3, 2HC1. 



