FOBMATION OP IND1QO-BLUE. 231 



the properties of indicanine. The lead compound which was 

 obtained in the form of a sulphur-yellow precipitate by adding 

 acetate of lead to the alcoholic solution, was after being 

 filtered off and washed with alcohol submitted to analysis 

 when it gave the following results: — 



1.2580 grm. dried first in vacuo and then in the waterbath, 

 gave 0.8320 grm. carbonic acid and 0.2040 water. 



1.5655 grm. gave 0.2740 grm. chloride of platinum and 

 ammonium. 



0.7620 grm. gave 0.6610 grm. sulphate of lead. 

 These numbers correspond in 100 parts to 



Carbon 18.03 



Hydrogen 1.80 



Nitrogen 1.09 



Oxygen 15.26 



Oxide of Lead 63.82 



100.00 



The oxide of lead being deducted, the substance combined 

 with it was found to have a composition agreeing with the 

 formula Cio H M NO*;, as will be seen by a comparison of 

 the calculated composition with that found by experiment : — 



Eqs. Calculated. Found. 



Carbon 40 240 50.20 85 



Hydrogen 24 24 5.02 4.98 



Nitrogen 1 14 2.92 3.01 



Oxygen 25 200 41.86 42.16 



478 100.00 100.00 

 When a watery solution of indican or indicanine is evapo- 

 rated in contact with the air, either spontaneously or with 

 issistance of heat a portion of it is always converted 

 into a substance which is insoluble not only in ether but 

 also in alcohol. That the formation of this substance is due 

 to the action of oxygen on indicanine is proved by analysis. 

 formation moreover is promoted by heating the solution 

 of indicanine with peroxide of lead, the filtered liquid after 



