Dr. Sclmnck on the Formation of Indigo-blue. 131 



It may further be assumed that 1 equivalent of indicari, after 

 taking up 4 equivalents of water, is decomposed into 1 equiva- 

 lent of indihumine, 3 equivalents of indiglucine, 1 equivalent of 

 propionic acid, and 2 equivalents of carbonic acid, as follows : — 



rc20H9 N0« 1 eq. indihumine. 

 leq.indicanC^^Hsi ^o^\ J C^^ H^o 0'-^'^ 2 eqs. indiglucine. 

 4eqs. water __H4_0^/1 C« H^ O'* 1 eq. propionic acid. 

 ^52 jj35]\jQ38 \_Q^ 0^ 2 cqs. carbouic acid. 



C.52H35N038 



The formation of indifuscone is quite analogous to that of in- 

 dihumine, the propionic acid in the preceding equation being 

 simply replaced by acetic acid, for — 



rC22 Hio NO^ 1 eq. indifuscone. 

 1 eq. indican C^^ h^i NO^^ -) J C^^ h^o q^* 2 eqs. indiglucine. 

 3 eqs. water H^ 0^ /I C* H^ 0^ 1 eq. acetic acid. 



C52 H*i NO^'' L^^ 0^ 2 eqs.carbonic acid. 



The manner in which indifuscine takes its rise from indican 

 needs no explanation, since a comparison of its formula C^'^H'^NO^ 

 with that of indifuscone shows that its composition differs from 

 that of the latter by containing in addition the elements of 2 

 equivalents of carbonic acid. In its conversion into indiretine, 

 indican splits up into 1 equivalent of the latter body, 1 equiva- 

 lent of indiglucine, and 4 equivalents of carbonic acid. Here, 

 however, the anomaly presents itself of a copulated body like 

 indican losing water instead of taking it up during its decom- 

 position into simpler compounds, as will be seen from the fol- 

 lowing equation : — 



rC36Hi7NO»oieq. indiretine. 



1 eq. indican C^^ H^^ NO^ = i ^f ^'° ns' ] '^^ i'^^'Sl""'^^-. , 

 ^ L^ U° 4 eqs. carbonic acid. 



t. H** 0'^ 4 eqs. water. 



It will be observed that when indican is converted into indigo- 

 blue or indirubine, it yields at the same time 3 equivalents of 

 indiglucine, whereas the formation of the other products of de- 

 composition is accompanied by the elimination of no more than 

 1 or 2 equivalents of that substance. Hence it may be inferred 

 that the appearance of these other products is due to a part of 

 the indiglucine undergoing a further decomposition from the 

 action of tlie acid, its elements, together with the residual por- 

 tion of the indican, affording the materials out of which the other 

 liroducts are formed. In fact, we may easily suj)posc indiglu- 

 cine, or perhaps more strictly speaking the group of atoms con- 



K2 



