206 MR. E. SCHUNCK ON THE 



decomposition is finally completed; that is to say, that there 

 exists another intermediate body containing 28 equivalents 

 of carbon. 



Of the red colouring matter, which I have called indi- 

 rubine, I have not yet obtained a sufficient quantity for 

 analysis. 



I have several times submitted indihumine, obtained on 

 different occasions, to analysis, but without being able to 

 arrive at any positive conclusion regarding its composition. 

 The difficulty of doing so arises from the circumstance of 

 this substance forming compounds with alkalies and other 

 bases which are not completely decomposed by acids. The 

 analyses which I have made agree best with the formula 

 Ci6 He NOs. If this be the correct formula, it differs in 

 composition from indigo-blue by the elements of three equi- 

 valents of water, just as the body or bodies from which it is 

 formed differ from indican by containing the elements of 

 several equivalents more water. 



The analyses of indiretine led to more definite results. 

 The substance was prepared from indican, which had under- 

 gone the alteration of which I have several times spoken, by 

 treating it with boiling sulphuric acid, collecting the dark 

 brown deposit which was formed, on a filter, washing out the 

 acid, treating with boiling alcohol, filtering from the indi- 

 humine which remained undissolved, and evaporating the 

 alcoholic solution to dryness. 



I. 0.4420 grm. dried in the waterbath and burnt with 

 oxide of copper and chlorate of potash gave 0.9930 grm. 

 carbonic acid and 0.2100 water. 



0.5470 grm. gave 0.3415 grm. chloride of platinum and 

 ammonium. 



II. 0.5370 grm. of another preparation gave 1.2130 grm. 

 carbonic acid and 0.2675 water. 



0.8780 grm. gave 0.4320 grm. chloride of platinum and 

 ammonium. 



