132 Dr. Schunck on the Formation of hidigo-blue. 



tained in indican which goes to form indighicine, to split up 

 into 1 equivalent of propionic acid, 1 equivalent of acetic acid, 

 and 2 equivalents of carbonic acidj for 



Qi2Hiooi2 = C6H6 0'* + C4H4 0'' + 2C02. 



Each of these subordinate groups of atoms, or any two of them, 

 may then be supposed to enter into combination with that por- 

 tion of the indican which goes to form indigo-blue or indirubine, 

 and which may be called its central nucleus. When, for instance, 

 indihumine is formed, 2 equivalents of indiglucine are produced 

 from the indican, whereas the third equivalent splits up into 

 acetic acid, propionic acid, and carbonic acid. The two latter 

 are set at liberty, and may be found among the volatile products 

 of decomposition, but the elements of the acetic acid unite with 

 the indigo-blue group of atoms, yielding by the combination in- 

 dihumine. In the case of indifuscone, the acetic and carbonic 

 acids derived from the third equivalent of indiglucine are set at 

 liberty, whereas the propionic acid combines with the indigo- 

 blue molecule constituting indifuscone. ludifuscine again may 

 be supposed to consist of indigo-blue, propionic acid and car- 

 bonic acid, acetic acid alone being in this case disengaged. In 

 the process of decomposition which leads to the formation of in- 

 diretine, only 1 equivalent of indiglucine is eliminated, and 4 

 equivalents of carbonic acid are disengaged, while the 2 equiva- 

 lents of propionic acid, as well as the 2 equivalents of acetic acid 

 derived from the other two equivalents of indiglucine, unite with 

 the indigo-blue nucleus to produce indiretine. When o-indiful- 

 vine is formed, it must be assumed that 1 equivalent of indiglu- 

 cine, after taking uj) 2 equivalents of water, splits up into 3 equi- 

 valents of formic acid, and a body represented by the formula 

 C6H6 02, as follows :— 



C12 Hio 012 + 2HO = 3C2H2 04 + C6 11^02. 



Now^ the last is the formula belonging to the aldehyde of pro- 

 pionic acid, and by adding to this formula that of indigo-blue, 

 the sum will represent the composition of a-indifulvine. The 

 more complicated formula given above for Z»-indifulvine, viz. 

 Q44 JJ19 ]\f2 03^ represents a compound of 2 equivalents of indigo- 

 blue, with a body whose formula is C^^H'^O^, and which is 

 therefore homologous with propylic aldehyde, its origin being 

 due to 2 equivalents of indiglucine, being decomposed in such a 

 manner as to give rise to formic acid and carbonic acid in accord- 

 ance with the following equation : — 



2C'^H"'Oi2 + 2HO = 5CMl2 0'» + 2C02 + C'2H'2 02. 



It will be observed in all these cases, with one exception, viz. 

 that of indihumine, that in the assumed combination of the ele- 

 ments of indigo-blue with those of these various acids, &c., one 



