a yellow, sweet smelling resin was left. 



A portion of the alcohol solution of the toxicodendrin 

 gave a dark coloration with ferric chloride, did not reduce 

 Pehling solution ana was slightly acid to litmus. 



To see whetrjer the toxicodendrin coula be hydrolyzed, 

 the reirainder was dissolved in alcohol and dilute sulphuric 

 acid was added. A fine, white precipitate was forired at 

 once Y/hich rose to the surface on standing as a light floc- 

 culent substance. The mixture was heated for several days on 

 a water-hath, filtered from unhydrolyzed resin ana the fil- 

 trate was neutralized and concentrated in the way already 



described. The solution obtained reduced Fehling solution. 

 Hot enough was obtained for further sugar tests, but all the 

 hydrolysis experiments point to the conclusion that the poi- 

 sonous substance is a rhamnoside, and is the source of the 

 sugar in the plant* 



The reaction with ferric chloride observed whenever a 

 lead compound of the poison is decomposed by hydrogen sulphide 

 may be explained by the formation of traces of gallic acid or 

 fisetin through the action of the weak acids present. 



The supply of purified poisonous tar having been exhausted 

 in the preceding experiments, further study of the active 

 principle is postponed until more can be prepared. It is 

 highly desirable to investigate the white precipitate formed 

 by addition of sulphuric acid to an alcoholic solution of the 

 -504 



