FORMATION OF INDIGO-BLUE. 233 



I. 0.8515 grm. of this precipitate dried first in vacuo and 

 then at 100° C. gave 0.7310 grm. carbonic acid and 0.1735 

 water. 



1.1640 grm. gave 0.2575 grm. chloride of platinum and 

 ammonium. 



0.5 185 grm. gave 0.3460 grm. sulphate of lead. 



II. 1.2640 grm. of another preparation gave 1.0495 grm. 

 carbonic acid and 0.2430 water. 



1.5500 grm. gave 0.2505 grm. chloride of platinum and 

 ammonium. 



0.7730 grm. gave 0.5250 grm. sulphate of lead. 



Hence the composition in 100 parts was as follows: — 



I. H. 



Carbon 23.41 22.64 



Hydrogen 2.26 2.13 



Nitrogen 1.38 1.01 



Oxygen 23.85 24.25 



Oxide of Lead 49.10 49.97 



100.00 100.00 



After deducting the oxide of lead the first analysis gives a 

 composition agreeing with the formula C40 H w N0 31 , whereas 

 the second leads to the formula C40 H23 NO32, as is shown by 

 a comparison of the calculated numbers with those deduced 

 from the above analyses. 



Eqa. Calculated. I. Eqs. Calculated. £1. 



Carbon . . 40 240 45.80 45.99 40 240 45.02 45.25 



Hydrogen 22 22 4.19 4.44 23 23 4.31 4.25 



Nitrogen.. 1 14 2.67 2.71 1 14 2.62 2.01 



Oxygen.. 31 248 47.34 46.86 32 256 48.05 48.49 



524 100.00 100.00 533 100.00 100.00 



If the second formula be adopted as the correct one it fol- 

 lows that indicanine is simply converted into oxindicanine 

 by taking up 8 equivalents of oxygen. The formation of in- 

 difuscine from oxindicanine takes place in consequence of the 

 separation from the latter of I equivalent of indiglucine, 4 



2H 



