230 MR. E. SCHUNCK ON THE 



simple relation to that of the other constituents, be deducted, 

 the composition of the body combined with it will be repre- 

 sented by the formula C 12 H 9 O n , which is that of anhydrous 

 indiglucine, as will be seen from the following calculation : — 



Eqs. Calculated. Found. 



Carbon 12 72 42.60 42.14 



Hydrogen 9 9 5.32 5.42 



Oxygen 11 88 52.08 52.44 



169 100.00 100.00 

 The manner in which indiretine and indifuscine are formed 

 from indicanine needs no explanation, since the composition 

 of the latter ditfers from that of indican merely by the ele- 

 ments of 1 equivalent of indiglucine. It is however difficult 

 to explain why indicanine by decomposition with acids should 

 yield only these products and no indigo-blue, indirubine, or 

 indifulvine, which might, as far as their composition is con- 

 cerned, be produced at the same time, and I am quite unable 

 to assign any cause for this phenomenon. It seems to me 

 very probable that the indiretine and indifuscine which are 

 formed when pure indican in large quantities is decomposed 

 with acids owe their origin to the conversion of a portion of 

 the indican into indicanine, before the acid has had time to 

 effect the more complete decomposition of this portion into 

 indigo-blue or indirubine and indiglucine. 



Indican is decomposed when its watery solution is heated 

 for a length of time, in exactly the same manner as by means 

 of alkalies. After the solution has been heated for some time 

 it no longer gives any indigo-blue when a portion of it is 

 boiled with sulphuric acid. If it be now evaporated in the 

 same apparatus as that used for evaporation of solutions of 

 indican it leaves a brown syrup, a great part of which dis- 

 solves in alcohol. On adding ether to the alcoholic solution 

 a syrupy deposit of indiglucine is produced followed by the 

 separation of crystals of leucine. If the liquid be filtered 

 and evaporated it leaves a brown glutinous residue having 



