nd to vary much as to dose, at different
seasons of the year; but I expected, if gathered always in one
condition of the plant, viz. when it was in its flowering state, and
carefully dried, that the dose might be ascertained as exactly as that
of any other medicine; nor have I been disappointed in this
expectation. The more I saw of the great powers of this plant, the
more it seemed necessary to bring the doses of it to the greatest
possible accuracy. I suspected that this degree of accuracy was not
reconcileable with the use of a _decoction_, as it depended not only
upon the care of those who had the preparation of it, but it was easy
to conceive from the analogy of another plant of the same natural
order, the tobacco, that its active properties might be impaired by
long boiling. The decoction was therefore discarded, and the
_infusion_ substituted in its place. After this I began to use the
leaves in _powder_, but I still very often prescribe the infusion.

Further experience convinced me, that the _diuretic_ effects of this
medicine do not at all depend upon its exciting a nausea or vomiting;
but, on the contrary, that though the increased secretion of urine
will frequently succeed to, or exist along with these circumstances,
yet they are so far from being friendly or necessary, that I have
often known the discharge of urine checked, when the doses have been
imprudently urged so as to occasion sickness.

If the medicine purges, it is almost certain to fail in its desired
effect; but this having been the case, I have seen it afterwards
succeed when joined with small doses of opium, so as to restrain its
action on the bowels.

In the summer of the year 1776, I ordered a quantity of the leaves to
be dried, and as it then became possible to ascertain its doses, it
was gradually adopted by the medical practitioners in the circle of my
acquaintance.

In the month of _November_ 1777, in consequence of an application from
that very celebrated surgeon, Mr. Russel, of Worcester, I sent him the
following account, which I choose to introduce here, as shewing the
ideas I then entertained of the medicine, and how much I was mistaken
as to its real dose.--"I generally order it in decoction. Three drams
of the dried leaves, collected at the time of the blossoms expanding,
boiled in twelve to eight ounces of water. Two spoonfuls of this
medicine, given every two hours, will sooner or later excite a nausea.
I have sometimes used