200 MR. E. SCHUNCK ON THE 



compound be precipitated from an alcoholic extract of woad 

 with acetate of lead and ammonia, if the precipitate be de- 

 composed, after washing with alcohol, by suspending it in 

 alcohol and passing a stream of carbonic acid through the 

 liquid, and the substance be again precipitated from the 

 filtered liquid by means of acetate of lead and ammonia, 

 the lead compound thus formed will be found to contain 

 besides indican a quantity of fatty matter, from which the 

 indican can only be separated by means of water, and its 

 analysis leads, as I have ascertained, to no satisfactory 

 results. It is, therefore, necessary to evaporate a watery 

 solution of indican spontaneously, to dissolve the residue in 

 alcohol, and precipitate with acetate of lead and ammonia, 

 taking care to leave a slight excess of indican in solution. 

 The following analysis was made with a specimen of the 

 lead compound prepared in this manner, the indican itself 

 having been obtained by the third method described above. 



I, 1.4340 grm. of the compound dried in vacuo and burnt 

 with oxide of copper and chlorate of potash gave 0.9600 

 grm. carbonic acid and 0.2860 water. 



1.2170 grm. gave 0.1700 grm. chloride of platinum and 

 ammonium. 



0.3790 grm. gave 0.3080 grm. sulphate of lead. 



These numbers lead to the following composition : — 



Eqs. Calculated. Found. 



Carbon 52 312 18.67 18.25 



Hydrogen 35 35 2.09 2.21 



Nitrogen 1 14 0.83 0.87 



Oxygen 38 304 18.23 18.88 



Oxide of Lead 9 1005.3 60.18 5979 



1670.3 -100.00 100.00 

 Notwithstanding the care, however, which I took in the 



