UK. 223 



It will be observed that when indican is converted into 

 indirubine it yields at the same time 3 equi- 



lts of indiglucine, whereas the formation of the other 

 products of decomposition is accompanied by the elimination 

 of no more than I 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 de- 

 composition from the action of the acid, its elements together 

 with the residual portion of the indican affording the materials 

 out of which the other products are formed. In fact we may 

 easily suppose indiglucine, or perhaps more strictly speaking 



-roup of atoms contained in indican which goes to form 

 indiglucine, to split up into 1 equivalent of propionic acid, 

 I equivalent of acetic acid, and 2 equivalents of carbonic 

 acid, for 



C« H 10 12 = C 6 H 6 4 + C 4 H 4 4 + 2 C (X 



Each of these subordinate groups of atoms or any two of 

 them may then be supposed to enter into combination with 

 that portion 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 



lucine are produced from the indican, whereas the third 



ralenft splits up into acetic acid, propionic acid, and car- 

 acid. The two latter are set at liberty and may be 



I 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 indihumine. 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 con- 

 stituting indifuscone. Indifuscine again may be supposed to 



st of indigo-blue, propionic acid and carbonic acid, acetic 

 acid alone being in this case disengaged. In the process of 

 decomposition which leads to the formation of indiretine, only 



livalent < icine is eliminated, and 4 equivalents of 



