KHITTEL'S INVESTIGATION.
The first attempt to find the poisonous constituent of this plant was made by Khittel in 1857. His work was published in Wittstein's Vierteljahrresschrift für praktische Pharmacie, VII, 348-359.[14] Khittel obtained 37-1/2 ounces of fresh leaves of poison ivy from the botanical garden in Munich, dried them, and got a residue of 9-1/2 ounces which he analyzed. Not detecting anything to which the poisonous qualities of the plant could be attributed, he made another series of experiments which, as he thought, showed that a volatile alkaloid is the poisonous constituent. It was obtained by the following process: "3 ounces of the powdered leaves were infused with hot distilled water, after three days strained, expressed, the liquid evaporated to 3 ounces, and with the addition of potassa, carefully distilled to one-half. The clear, colorless distillate had an alkaline reaction, and an odor resembling henbane or hemlock. It was saturated with sulphuric acid, evaporated, and treated with a mixture of equal quantities of alcohol and ether which left sulphate of ammonia behind, the solution was evaporated spontaneously, distilled with potassa, the alkaline distillate neutralized with hydrochloric acid, and a precipitate could now be obtained with chloride of platinum. Want of material prevented further experiments."
The editor of the American Journal of Pharmacy inserts the following note: "It would have been more satisfactory if the author had given some physiological evidence of the poisonous nature of the alkaloid substance obtained. It is quite interesting to hear that the hitherto intangible venom of this plant has at last been detected."