192 MR. E. SCHUNCK ON THE 



quantity of sulphuric acid, and the green fatty matter precipi- 

 tated by the acid was separated by filtration. The action of 

 the acid passed, as I invariably observed, through two distinct 

 stages, and I found it convenient to collect and treat the 

 products formed at each stage of the action separately. The 

 filtered liquid, though clear at first, soon became opalescent 

 and muddy and deposited dark flocks, while the surface became 

 covered with a blue pellicle. After the liquid had stood in 

 the cold for about twenty-four hours, this deposit usually 

 ceased to be formed, and the action then entered on its second 

 stage, which was manifested by the separation from the filtered 

 liquid of a brown powder the quantity of which was much 

 increased by heating. This powder contained little or no 

 indigo-blue, but some indirubine and a large quantity of other 

 products of decomposition. I think it probable that the first 

 deposit owed its origin to the pure indican contained in the 

 solution, while the second was formed from indican that had 

 undergone a change by the action of water. The matter 

 insoluble in water formed by the action of acid having been 

 collected on a filter, the acid liquid was employed for the 

 preparation of the other products of decomposition in a manner 

 to be hereafter described. The portion of the products in- 

 soluble in water was also obtained by another method, still 

 more expeditious than the one just described. The leaves of 

 the plant having been finely chopped, boiling water was poured 

 over them, and the mixture having been well stirred the liquid 

 was strained through calico and mixed with sugar of lead. 

 This produced a pale green precipitate which was separated 

 by filtration, and the liquid having been mixed with an excess 

 of sulphuric acid was filtered from the sulphate of lead and 

 heated for some time, when it produced a deposit containing 

 the same products as before. Instead of sulphuric acid I 

 sometimes employed nitric acid, avoiding however in this case 

 the use of heat. More indigo-blue and less of the other pro- 



