638 [June 18, 



have mentioned sufficient by itself to establish the non-identity of 

 munjistine and rubiacine" *. 



The purpurine which I succeeded in extracting from munjeet and 

 in purifying from munjistine in the way already described, formed 

 beautiful dark crimson needles, having all the usual properties of 

 that substance. "When examined by Professor Stokes, they gave the 

 very characteristic spectra of purpurine. 



3285 grm. of purpurine gave '8005 grm. carbonic acid and *1050 



grm. water. 



Analysis. 



Theory. 



c 



H 



29-63 



100-00 100-00 100-00 



From the results above detailed there can therefore be no doubt 

 that the colouring matter of munjeet, as already stated, consists of 

 purpurine and munjistine. 



I cannot conclude this preliminary notice without acknowledging 

 the essential services I have received from Professor Stokes, who 

 kindly submitted the different products obtained by me to optical 

 examination. Though it is plain that a substance optically pure, 

 that is, containing no impurities affecting the spectrum, may still 

 be far from being chemically so, yet the spectroscope is extremely 

 useful in indicating admixtures of kindred substances of very similar 

 properties, having a great affinity for each other, and therefore 

 not readily separable. I feel certain therefore that if Professor Stokes 

 would draw up a short treatise embodying his extensive and accurate 

 observations on the spectra of the colouring matters and similar 

 substances, he would confer a great boon on the cultivators of orga- 

 nic chemistry. 



POSTSCRIPT. Received July 18, 1863. 



Since the preceding paper was communicated to the Royal Society 

 I have been enabled to examine the action of nitric acid on munjis- 



* I may mention that the rubiacine which Professor Stokes examined was 

 prepared by Dr, Schunck himself. 



