This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
This is the botanical name of a genus of plants of the umbelliferous class, of which there are three species natives of Great Britain. One of these only is known by its effects on the human body, the Oenanthe Chaerephylli foliis C. B. Oenanthe crocata Linn, Hemlock dropwort: this is a large umbelliferous plant, growing in ditches and other moist places; with pinnated leaves, resembling those of celery or chervil, and ribbed stalks. Its roots afford the easiest mark of distinction, which are white, thick, and short, and grow several together, forming a kind of bunch.
The hemlock dropwort has long been known as a most dangerous poison; the mod virulent, perhaps, that this country produces. Its roots or leaves eaten by mistake, have frequently proved fatal, occasioning violent sickness and vomiting, rigors, convulsions, delirium, and other terrible affections of the nervous system. The head has been said to be affected even by being in the same room with a quantity of the plant. Like so many other deleterious vegetables, it, however, is capable of being rendered a powerful remedy. A case is published by Dr. Pulteney in the Philos. Tranfact. vol. lxii. in which this plant, used by mistake instead of the water parfnep, proved remarkably efficacious in removing an inveterate scorbutic complaint, which had refilled a variety of other remedies. The dose first given was a common spoonful of the juice of the root, which at the first exhibition produced very alarming effects. This was afterwards reduced to three tea-spoonfuls; which quantity was persisted in a considerable time, and then changed for a tea of the leaves. The medicine never proved purgative, but was diuretic. It always occasioned a degree of vertigo; accompanied, when the juice itself was taken, with nausea and sickness.
(a) Observsationes physico-chymicae, lib. i. obf. 4.
If this experiment be imitated, it is obvious that the greatest degree of caution will be necessary.