HYPERICUM PERFORATUM. 
25 
nite quantity of those parts of the plant said to contain it. I 
attempted to procure some of this principle by distillation, 
but failed in the experiment, and in consequence of my supply 
of the herb being small, I was obliged to abandon further pro- 
ceedings. The only evidence I had of the presence of a vola- 
tile oil in this plant was, that when a branch of it was im- 
mersed in a vessel containing water heated nearly to the 
boiling point, a thin stratum of a volatile substance was evi- 
dent, floating on its surface, the whole presenting such an ap- 
pearance as it otherwise would have done, had a drop of one 
of the ordinary essential oils been substituted for the branch 
of Hypericum. From the several experiments just described 
I think it is reasonable to suppose, that the only proximate 
principles of importance contained in the St. John's Wort, 
are an acrid resinous substance, probably a small portion of 
volatile oil, tannin, and a red colouring matter. To the first 
of these it is probable the plant owes, in a great measure, its 
medical virtue. 
St. John's Wort has been employed as a therapeutic agent 
as long since as the time of Hippocrates. Like many other 
medicines of long standing, at different periods different opi- 
nions were entertained of its efficacy. At one time, its virtues 
were the subject of the highest encomium; again it was regarded 
as almost or entirely inert; and again, it was introduced, and 
acquired celebrity, so that we are almost induced to believe it 
to be of but little, if of any, importance. Some of the ancient 
practitioners, however, formed a high estimate of its impor- 
tance in the treatment of those afflicted with mental derange- 
ment and epilepsy. 
It is said to be possessed of anthelmintic and diuretic pro- 
perties. Dr. Cullen, in treating of this medicine, says: "I 
confess I do not understand how it can act, but though in- 
deed there are testimonies of its virtues in epileptic and ma- 
niac cases." The same author also states, that "there are 
many well vouched testimonies of its virtues, particularly of 
its diuretic powers." 
If St. John's Wort really does possess these properties, it 
vol. II. — no. i. 4 
