FORMATION OF INDIGO-BLUE. 235 



0.8895 grm. gave 0.6485 grm. sulphate of lead. 

 These numbers lead to the following composition :— 



Eqt. Calculated. I II. 



Carbon 28 168 20.27 20.1* 20.91 



Hydrogen... 16 16 1.93 1.97 2.00 



Nitrogen .... 1 14 1.68 1.70 1.70 



Oxygen 23 184 22.22 21.71 22.35 



Oxide of Lead 4 446.8 53.90 54.44 53.04 



828.8 100.00 100.00 100.00 

 The following table shows the composition of the substance 

 after deducting the oxide of lead as compared with that re- 

 quired by theory : — 



Eqs. Calculated. I. II. 



Carbon 28 168 43.97 44.29 44.52 



Hydrogen ... 16 16 4.18 4.32 4.25 



Nitrogen 1 14 3.66 3.73 3.62 



Oxygen 23 184 48.19 47.66 47.61 



382 100.00 100.00 100.00 

 This body may for the sake of distinction be called Oxin- 

 dicasine. It is formed from oxindicanine by the latter taking 

 up water and losing 1 equivalent of indiglucine, since 

 1 eq. Oxindicanine C^ H.^ NO*, \ __ ( C w H l6 NO^ 1 eq. Oxindicasine 

 3 eqs. Water H 3 O, i ~~ ( C ia H 10 O n 1 eq. Indiglucine. 



C4oH»NO M C^H^NO* 



It is possible that there may exist a body which bears to 

 oxindicasine the same relation that indicanine does to oxin- 

 dicanine. This body would be Indicasine, and would differ 

 from indicanine by containing the element of 1 equivalent of 

 indiglucine less. The following analyses of a lead compound 

 which was obtained a* a pale yellow precipitate when a large 

 quantity of alcohol was added to the liquid filtered from the 

 lead compound of oxindicasine, seem to countenance the idea 

 that such a body really exists. 



I. 0.9705 grm. of this precipitate, alter being completely 

 washed with alcohol and then dried, at first in vacuo and then 



