Dr. Schunct on the Formation of Indigo-blue. 189 



I. II. 



Carbon 23-41 22-64 



Hydrogen 2-26 2-13 



Nitrogen 1-38 I'Ol 



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 C^H^^NO^i, whereas 

 the second leads to the formula C" H^^ NO^^, as is shown by a 

 comparison of the calculated numbers with those deduced from 

 the above analyses. 



Eqa. Calculated. I. Eqs. Calculated. II. 



Carbon'.... 40 240 45-80 45-99 40 240 45-02 45-25 



Hvdroffen.. 22 22 4-19 444 23 23 4-31 425 



■ Nitrogen ..1 14 2-6/ 2-71 1 14 2-62 2-01 



Oxygen .... 31 248 47-34 46-86 32 256 48-05 J8;49 



524 100-00 100-00 633 10000 10000 



If the second formula be adopted as the correct one, it follows 

 that indicanine is simply converted into oxindicanine by taking 

 up 8 equivalents of oxygen. The formation of indifuscine from 

 oxindicanine takes place in consequence of the separation from 

 the latter of 1 equivalent of indiglucine, 4 equivalents of car- 

 bonic acid, and 3 equivalents of water, in accordance with the 

 following equation : — 



rC24HioN09 leq. Indifuscine. 



^ . ,. • ^dr.TTo<,ATr^<,9 J Ci^H'o 012 leq. Indiglucine. 

 leq.OxmdicanmeC^0H23NO32 = ^ ^, qs 4eqs.Cai-bonicacid. 



L H3 03 3 eqs. Water. 



The acetic acid which is produced when indifuscine is formed 

 from indicanine does not make its appearance in this case. 

 Indeed the 8 equivalents of oxygen which indicanine absorbs in 

 its conversion into oxindicanine are just sufficient, when added to 

 the oxygen already contained in 1 equivalent of acetic acid, to 

 convert the carbon and hydrogen of the latter into carbonic acid 

 and water. 



"VVhcn a solution of indican is evaporated in contact with the 

 air with the assistance of heat, and the residue which remains is 

 treated with strong alcohol, there is left undissolved a brown 

 glutinous suljstance, wliich has the properties of oxindicanine, 

 but a different composition. The lead compound of this sub- 

 stance was prepared by dissolving the latter in water, adding 

 acetate of lead, decomposing the precipitate with sulphuretted 



