55 



of these seemed to give anything more than a temporary relief. 

 The best results were obtained by rubbing the surface with a little- 

 petrolatum and then scraping it off with a knife and washing the 

 surface with a weak solution of sodium hydroxide or carbonate. 

 The burning on the face was relieved by keeping it moistened 

 with a saturated solution of boric acid. > 



Dr. Jadassohn, Professor of Skin Diseases in the University 

 of Bern, stated that the above symptoms did not prove that the 

 poisonous principle was volatile, and kindly volunteered to make 

 the physiological tests for me in order to determine whether the 

 poisonous principle is volatile or not. He found that the rabbit 

 was very sensitive to the poison. The method of testing was to 

 rub a small quantity of the substance on the inside of the ear for 

 2 or 3 minutes. If poisonous, inflammation appeared in from 

 i to 5 days and the surface soon became covered with watery 

 blisters followed, in severe cases by necrosis of the superficial 

 layers of the skin. This condition lasted about 14 days when it 

 gradually disappeared. 



The following are the most important results obtained from 



the tests : 



1. Sterilized lac, prepared by suspending a tube of the lac in 

 boiling water for half an hour, was poisonous. 



2. An alcoholic solution of the lac was distilled and the dis- 

 tillate tested but was not poisonous. 



3. After the alcohol was removed, the distillation was con- 

 tinued when a small quantity of aqueous distillate was obtained, 

 but this was also inactive. 



4. The residue in the retort was extremely poisonous. 



5. A fresh can of lac was thoroughly cooled to prevent the 

 escape of gas while opening, two small openings made, and tubes 

 introduced. A small quantity of absorbent cotton was placed 

 in the tube, used for the exit of vapor, to prevent particles of the 

 fluid from being forced through. The vapor was then slowly 

 forced out of the can upon the ear of a rabbit. Part of the ear 

 had previously been moistened. The vapor was entirely without 

 action. Since then I have worked over the lac, while evaporating 

 it under all conditions without the slightest inconvenience. 



6. The alcoholic residue was later separated into two parts, 

 one soluble and the other insoluble in benzin. The first was 



