190 



SCIENTIFIC AND APPLIED PHARMACOGNOSY 



the solutions having a deep-red color. It is reformed in rhubarb 

 after extracting it by exposing the moistened root to air. Emodin 



FIG. 80. Rheum officinale, growing in the Chelsea Physic Garden (London).' 



After Perredes. 



occurs to the extent of 1.5 per cent and forms orange-red needles 

 which are soluble in hot toluene and give with alkalies and alkali 



