62 Messrs. Stenliouse and Groves on Picrorocellin. [May 18_, 



I. '263 gram sabstauce gave '657 gram carbonic anhydride and -151 

 gram water. 



II. -178 gram substance gave -444 gram carbonic anhydride and -100 

 gram water. 



III. -218 gram substance gave '02285 gram^ ammonia, 

 ly. '215 gram substance gave '02219 gram ammonia. 







Theory. 



I. 



II. 



III. 



IV. 



Mean. 





. 324 



68-21 



68-13 



68-03 







68-08 





. 29 



6-11 



6-38 



6-24 







6-31 





. 42 



8-84 







8-63 



8-50 



8-56 





. 80 



16-84 















475 



100-00 













The numbers obtained from the results of these analyses agree very 

 closely ^^dth those required by the formula C^Jl.^^'Nfi-. As this com- 

 pound is obtained from a species of Rocella and possesses an exceedingly 

 bitter taste, we purpose ci\\liTigit picrorocellin. It is remarkable as being 

 the first crystalline organic substance containing nitrogen which has been 

 found in "the lichens. 



Occasionally specimens of Rocella are met with which have a coui- 

 paratively feeble bitter taste ; but hitherto we have been unable to isolate 

 any crystalnue compound from them to which this property might be 

 ascribed. 



We have not, as yet, examined the second substance crystallizing in 

 minute, difficulty soluble needles, and which accompanies picrorocellin in 

 this lichen, but hope to be able to do so ere long. We have ascertained, 

 however, that it is not merely a fatty substance of a nature similar to 

 roceUic acid, since on boihng it with a dilute solution of sodic hydrate, 

 benzoic aldehyde appears to be produced. 



XantJiorocellin. 



When picrorocellin was heated above its fusing-point it decomposed, the 

 products obtained varying with the temperature. When strongly heated, 

 water and ammonia were given oS, and a brown oily body distilled, which 

 on being put aside for some time deposited crystals. These, after being 

 separated from the fluid portion and recrystallized two or three times from 

 spirit, formed colourless plates which are moderately soluble in alcohol but 

 insoluble in water. This substance has been reserved for further inves- 

 tigation. 



If, however, instead of subjecting the picrorocellin to destructive distil- 

 lation it was merely heated for about ten minutes to 220°, it gave off 

 water, and the fluid product if poured out and allowed to cool solidified 

 to a resinous-looking mass. This, when finely powdered and dissolved in 

 about three times its weight of boihng spirit, solidified on cooling to a pulp 

 consisting of long, slender, yellow needles of xanthorocellin. This sub- 



