J) r. Schunck 071 the Formation of Indigo-blue. 185 



1-0350 grm. gave 0-3225 grm. chloride of platinum and am- 

 moniuni. 



0-3785 grm. gave 0-3010 grm. sulphate of lead. 

 Hence was deduced the following composition : — 



1139-2 100-00 100-00 



After deducting the oxide of lead, the amount of the other 

 constituents in 100 parts, as compared with the calculated com- 

 position, is as follows :- 



In the first part of this paper I gave an analysis of the lead 

 compound of a substance having the formula C''^ H^^ NO^'', which 

 differed therefore in composition from this merely by containing 

 the elements of 3 equivalents more of water. As it was impos- 

 sible to analyse these substances in an uncombined state, there 

 were no means of ascertaining whether in that state they had 

 the same composition, as was most probably the case. 



Indicanine is formed from indican simply by the latter taking 

 up water and losing 1 equivalent of indiglucine, as will be seen 

 from the following equation : — 



1 eq. Indican C^^ H^i NO^n _ /C^OH^^NO^^ 1 eq. Indicanine. 



2 eqs. Water H^ 0^ J - XC'^H^o 0'^ 1 eq. Indiglucine. 



C^2H33N036 C52H33N036 



The indiglucine formed in the process is contained in the 

 brown syrupy deposit which falls on adding tether to the alco- 

 holic solution of the indicanine. Some of this deposit, after the 

 liquid had been poured off, was dissolved again in alcohol ; the 

 solution was mixed with an excess of alcoholic solution of acetate 

 of lead, which produced a brown glutinous precipitate, and to 

 the filtered liquid was added an excess of ammonia, which gave 

 a bulky sul])hur-ycllow precipitate. This precipitate was col- 

 lected on a filter, washed with water, and decomposed with sul- 

 phuretted hydrogen, and the filtered liquid was agitated with 



