Leaves and flowers of the poison ivy plant were extracted with ether and
the ether was removed by evaporation. In the residue, the following
substances were found and studied: gallic acid, fisetin, the sugar
rhamnose, and a poisonous tar, gum, or wax.
The lead compound of the poison was soluble in ether; this fact gave a
means of separating the poisonous substance from the non-poisonous
matter in one operation.
The poison was not volatile with vapor of acetic acid, or with vapor of
alcohol.
The poisonous tar or wax was decomposed by acids and yielded gallic
acid, fisetin, and rhamnose, showing the probable source of these
compounds in the plant, and indicating that the poison is a complex
substance of a glucoside nature.
It was found that a portion of the poisonous substance could be
precipitated by lead acetate from a solution of the purified tar in 50
per cent. alcohol.
All cases of poisoning developed on the writer were easily cured with
potassium permanganate.
The following method is suggested for obtaining the poisonous substance
from the plant: Extract the plant with alcohol, filter, and precipitate
at once with lead acetate. Wash the precipitate, dry, and extract with
ether in Soxhlet extractors (loosely filled). Combine the ether
extracts, mix with water, and pass in hydrogen sulphide. Separate the
water and the ether solution, and filter the latter. Wash the ether
solution thoroughly by shaking with water, and then evaporate at a low
temperature.