204 MR. E. SCHUNCK ON THE 



an examination of the properties of the former leaves little 

 doubt concerning their identity. I regret not having as yet 

 been able to ascertain by analysis, whether this is the case 

 or not, as I have devoted the whole of the material at my 

 disposal to an investigation of the properties and composition 

 of indican itself. 



I also assume that indican in undergoing decomposition 

 with acids splits up immediately into I equivalent of indigo- 

 blue and 3 equivalents of sugar. It is, however, possible 

 that these three equivalents of sugar may not be eliminated 

 all at once ; and from one analysis which I made, I should 

 conclude that they separated successively. Having ex- 

 tracted some dried woad leaves with cold ether, I poured 

 the etherial extract into a large bottle, and agitated it with 

 about half its volume of cold water. The ether was poured 

 off, and the watery liquid was employed again for agitation 

 with several successive portions of etherial extract of woad. 

 It acquired at last a dark yellow colour. The ether con- 

 tained in it was removed by spontaneous evaporation, and 

 it was then evaporated under a bell over sulphuric acid. 

 At first it yielded indigo-blue when boiled with sulphuric 

 acid; but the evaporation having been conducted in too 

 warm a place, the indican contained in it became changed, 

 and it ceased to give blue flocks with acids. After the 

 evaporation was completed there was left a brown syrupy 

 residue, which was redissolved in alcohol. Acetate of lead 

 produced in the alcoholic solution a cream-coloured preci- 

 pitate which was separated by filtration, and on adding a 

 small quantity of ammonia to the filtered liquid, a cream- 

 coloured precipitate again fell, which was collected on a 

 filter, washed with alcohol, and dried in vacuo. On ana- 

 lyzing it I obtained the following results : — 



0.3705 grra. burnt with oxide of copper and chlorate of 

 potash gave 0.2670 grm. carbonic acid and 0.0730 water. 



