FORMATION OF INDIGO-BLUE. 205 



0.3800 grra. gave 0.0680 grm. chloride of platinum and 

 ammonium. 



0.2680 grm, gave 0.2160 grm. sulphate of lead. 

 In 100 parts it contained, therefore, ' 



Carbon 19.65 



Hydrogen 2.18 



Nitrogen 1.12 



Oxygen 17.75 



Oxide of Lead 59.30 



100.00 



After deducting the oxide of lead, the amount of which 

 stands in no simple relation to that of the other consti- 

 tuents, the organic substance combined with the oxide of 

 lead will be found to have a composition expressed by 

 the formula C40 Hge NO27, ^^ will be seen by the following 

 calculation : — 



Eqs. Calculated. Found. 



Carbon 40 240 48.38 48.28 



Hydrogen 26 26 5.24 5.35 



Nitrogen 1 14 2.82 2.75 



Oxygen 27 216 43.56 43.62 



496 100.00 100.00 



This body is, therefore, formed from indican by the latter 

 taking up 3 equivalents of water and then losing 1 equiva- 

 lent of sugar, as will be evident from the following equa- 

 tion : — 



1 eq. Indican Cgj H33 NOje ) TC^o ^26 ^Og, 



3 eqs. Water H3 O3 ) (CiaHjo O12 1 eq. Sugar. 



CoHaeNOao C^ll^^NO» 



It is perfectly conceivable that an additional equivalent of 

 sugar may separate from the body C40 H^ NO,; before the 



