The greasy, semi-solid mass was extracted with 10 per cent. hydrochloric acid and filtered. On addition of a solution of mercuric chloride to the red filtrate, a brown flocculent precipitate was formed. It was filtered off and distilled with caustic soda, but the distillate did not contain pyridine. POTASSIUM PERMANGANATE AS A REMEDY FOR RHUS POISONING.[46] In the early stages of this work some experiments were made to see if potassium permanganate could be used to purify the lead precipitate by oxidizing the tar brought down in precipitation. It was found that the permanganate attacked the lead precipitate as well as the other organic matter in the vessel. This fact and the well-known value of permanganate in treating skin diseases, its use as an antidote for some kinds of alkaloid poisoning,[47] as an antidote given to cattle poisoned by plants,[48] and as an antidote for snake bites,[49] suggested its use as a remedy for Rhus poisoning. Maisch[50] mentioned that he had used it with success, but it never came into general use, probably on account of its staining the skin and clothing. In carrying out this work abundant opportunities for testing its value as a remedy for the dermatitis caused by poison ivy were afforded by many cases of accidental and intentional poisoning. The best example of the latter was obtained with the ether solution from the extraction of the lead precipitate in the Soxhlet apparatus (page 28). After removing the ether, a small drop of the residue was applied to the wrist as described. An itching red spot about the size of a dime was noticed in thirty-six hours, and it steadily increased in size. Nearly two days after the application of the poison, a dilute solution of potassium permanganate containing a little caustic potash was rubbed into the spot until the pimples were destroyed. A little black spot was left wherever there had been a pimple, showing that the permanganate had been reduced to oxide in the skin. The place was washed and nothing more was thought of it until the morning following, when it was noticed that the wrist had commenced to swell during the night, and the characteristic watery secretion was running from the poisoned spot. More permanganate solution was applied without potash and the wrist was bandaged, thinking that this would prevent the spreading of the eruption, but it really facilitated spreading by becoming saturated with the poisonous fluid and keeping it in contact with a larger surface of skin. In the meantime the swelling and inflammation had extended nearly to the elbow. The arm now had the appearance of having been bitten by a snake. To reduce the swelling it was immersed in hot water. This seemed to bring out the eruption very quickly and the blisters were treated with permanganate as fast as they appeared. The swelling was reduced, but returned during the night. On the evening following, the forearm was immersed in a bowl of hot