pounds with armnonitUD sulphide, shaking out with ether, and 

 letting the ether evaporate spontaneously, a non- volatile 

 oil was obtained which gave the characteristic skin erup~ 

 tions. The pure lead compounds made in different prepara- 

 tions were analyzed and assigned the formula Gg-j^H^QO^Pb, 

 The oil itself was not analyzed. Pfaff proposed the name 

 Toxicodendrol for the oil. He found that it was not vola- 

 tile, was decomposed by heat, was soluble in alcohol, ether, 

 chloroform, benzene, etc., but insoluble in water. Its 

 effects upon the human skin were studied in many experiments 

 upon himself and others. It was shown that an exceedingly 

 minute quantity of the poison will produce the dermatitis, 

 even l/lOOO mg. applied in olive oil being active. The oil 

 was given internally to rabbits, its effects being most marked 

 on the kidneys. 



The oil obtained by Pfaff from IQius venenata seemed to 

 be identical with that from Rhus toxicodendron . 



EZPERIMSHTAL. 



The writer's Investigation was undertalien with the 

 object of attempting to throw more light on the chemical 

 nature of the poisonous substance found in Rhus toxicodendron. 

 Soon after commencing work, however, it became apparent that 

 the poison could be more intelligently studied if the sub- 



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