196 MR. E. SCHUNCK ON THE 



process the indican acquires a brown colour and becomes 

 quite insoluble in cold alcohol, but it still dissolves, though 

 with difficulty, in boiling alcohol. By continuing the pro- 

 cess the substance acquires a dark brown colour, and its 

 watery solution now gives a copious precipitate with acetate 

 of lead. As soon as the indican has entered even on the 

 first stage of this process of change, it ceases to give the 

 least trace of indigo-blue with acids. A short period occurs 

 at the commencement of the process, during which the 

 watery solution when boiled with sulphuric acid deposits 

 purple flocks consisting of indirubine only. Afterwards, 

 however, it yields other products, which are always the same 

 at every subsequent stage of the process. If the watery 

 solution be then boiled with the addition of sulphuric or 

 muriatic acid, it becomes in the first instance of a darker 

 colour, and after considerable boiling deposits slowly a quan- 

 tity of dark brown, almost black flocks. The liquid filtered 

 from these flocks contains sugar, just as in the case of 

 indican itself. The flocks themselves generally consist of 

 two bodies. If they be collected on a filter, washed with 

 water and then treated with boiling alcohol, a part dissolves 

 with a brown colour, and after filtration and evaporation is 

 left as a dark brown shining resinous substance. This sub- 

 stance melts in boiling water into brown coherent masses. 

 It is completely dissolved and decomposed by boiling nitric 

 acid. It dissolves in ammonia with a brown colour, and the 

 solution gives brown precipitates with the chlorides of barium 

 and calcium. It is completely precipitated from its alcoholic 

 solution by sugar of lead, the precipitate being brown. I 

 propose to call this body Indiretine. That portion of the 

 dark brown flocks which is insoluble in boiling alcohol, dis- 

 solves in caustic alkalies with a dark brown colour, and is 

 precipitated by acids in black flocks. As it bears some re- 

 semblance in its outward properties to humus, I shall call it 



