A right composition of the several articles used in medicine, is of so
much importance to the practice of it, that every attempt to improve
or ascertain the method of preparing them, cannot fail of a candid
reception from the public.
Though great advancement has been made within these few years in
chemical pharmacy, by the labours of the very ingenious Dr. Lewis,
and some other writers on chemistry and the materia medica, there
is still a wide field left for improvement. It is to be wished that
Apothecaries, to whose province researches of this kind more peculiarly
belong, and many of whom are well qualified by a liberal education
to pursue them with advantage, would give their attention to these
material interests of the art: for while the several professors of
medicine and of surgery, are most laudably and assiduously employed in
adding to the enlargement of these sciences, why should the sons of
pharmacy remain supinely inactive, and leave every thing towards the
improvement of their profession to be performed by the members of the
elder branch of physic, instead of contributing _their_ share to its
support? as if tacitly acknowledging themselves unequal to the task,
and thereby incurring the too general, though unmerited, imputation of
want of knowledge and skill in their department.
The first part of the ensuing Treatise, which relates _an improved
method of preparing Magnesia Alba_, has been communicated to the
College of Physicians; and that learned body have done the author the
honour to insert it in the second volume of their TRANSACTIONS. It is
here reprinted as a proper introduction to the subsequent pages.
The calcination of Magnesia is not a new process[a]; but, as in this
state it is a medicine not much introduced into practice, perhaps a few
hints may be suggested, in regard to its medicinal and pharmaceutical
properties, which are not generally known; and it is hoped that some
useful information may be communicated relative to the various action
of absorbent medicines on the bile.
[a] The German and Italian chemists formerly prepared Magnesia by
evaporating the mother of nitre, and then calcining the residuum;
but, Hoffman having discovered the method of precipitating it from
the bittern remaining after the crystallization of sea salt, the
calcination was disused, as tedious and unnecessary.
In the succeeding chapters, it is attempted to determine how far,
and in what proportion, lime promotes the solution of vegetable
astringents, and other drugs in water; and whether the action of
antiseptic medicines, thus dissolved, be in any degree impaired or
increased by this mode of obtaining tinctures from them.
In endeavouring to contribute to the determination of the question,
whether fixed air has the power of restoring sweetness to putrid
substances, the Author may at first sight appear to have transgressed
his proper limits; but, as fixed air, if possessed of this property, is
likely to be a valuable acquisition to the materia medica, he flatters
himself he shall incur no censure by the attempt.