the Rheum Falmatum, or Rhubarb, 289 



by the acetate of lead, so as to leave the supernatant liquor 

 almost colourless. The precipitate by nitric acid was most co- 

 pious when a few drops of acid were added to the concentrated 

 infusion ; it had the character of resinous matter, and was pro- 

 bably altered extractive. It was again dissolved by nitric acid 

 added in excess. The precipitate by gelatine was most copious 

 in the cold infusion ; it scarcely formed in the hot infusion, and 

 watj re-dissolved by adding excess of the solution of isinglass. 



5. One hundred grains of the bruised root were digested re- 

 peatedly in fresh portions of alcohol, (specific gravity 8.15,) 

 till it exerted no further action, and came off perfectly colour- 

 less. The residue weighed, when dried at 212°, 55.8 grains, it 

 was insipid, and when put into water it softened and gave by 

 long digestion a viscid solution. When subsequently dried, it 

 was found to have lost 31 grains, which, obtained by evapora- 

 tion, had all the characters of gum ; it was insoluble in alcohol 

 and did not affect solution of iodine. 



6. The alcoholic solution was of a deep yellow colour, and had 

 a peculiarly nauseous taste ; it was concentrated by distillation, 

 and carefully evaporated to dryness : it left a brown residue 

 weighing 36 grains, which being triturated with cold distilled 

 isvater and poured upon a filter was resolved into 10 grains of 

 insoluble resin and 26 grains of soluble matter. 



7. The resin amounting to 10 grains was of a brown colour, 

 gave out an aromatic odour when burned, and entirely dissolved 

 in sulphuric ether. 



8. The 26 grains of matter soluble in water, were obtained by 

 evaporation, and afforded, upon being re-dissolved, a clear brown 

 aqueous solution, which rendered solution of isinglass turbid, 

 blackened solution of iron, and formed a copious precipitate 

 with acetate of lead: this residue, therefore, was chiefly extract 

 and tan. 



9. From the above experiments it appears that 100 parts of 

 rhubarb contain 



Gum 31. 1 -_ o . ,_ . 



)» 55.8 grams (5.) 

 Wood and insoluble residue 24.8J 



