_Mucilaginous_ Extracts of Rouelle.
These extracts must, of course, contain all the principles of a plant
which are soluble in water, such as gum, extractive matter, tannin,
cinchonin, sugar, fecula, &c. together with any soluble salts which the
vegetable may contain. I have also found by experiment that an aqueous
extract may even contain, in small proportions, certain elements which,
although quite insoluble in water, are nevertheless partially soluble in
vegetable infusion. This law of vegetable chemistry has never been
expressed, although we have repeated instances of its truth, and a
knowledge of it may explain some hitherto unintelligible anomalies. It
has been stated that extractive matter is perfectly insoluble in æther,
but Mr. A. Thomson found repeatedly, that if a small portion of resin
was present, æther would in that case take up extractive in combination
with the resin which it so readily dissolves. As decoction or infusion
is a process preliminary to that of extraction, the practitioner must
refer to those articles for an enumeration of the different sources of
error which are attached to them.
EXTRACTUM ALOES PURIFICATUM. L. The resinous element of the aloes is got
rid of in this preparation; on which account it is supposed, in an equal
dose, to be more purgative and less irritating. _Dose_, gr. x to xv.
_Form: 12, 13, 36._
EXTRACTUM ANTHEMIDIS. L.E. _Extract. Florum Chamœmeli._ D. This extract
furnishes an example of the change effected on some plants by the
process of extraction; in this case the volatile oil is dissipated, and
a simple bitter remains, possessing scarcely any of the characteristic
properties of chamomile. This remark, however, does not apply to this
extract, when prepared _in vacuo_. I have lately received from Mr. Pope
of Oxford Street, a specimen which retains, in the most eminent degree,
all the odour and taste of the recent flower. _Dose_, gr. x–℈j.
EXTRACTUM CINCHONÆ. L.D. The properties of the bark in this preparation
are much invalidated, owing to the oxidizement of its extractive matter,
which takes place to such an extent, that not more than one half of the
preparation is soluble in water; it is not however altogether devoid of
utility, and will often sit lightly on the stomach, when the powder is
rejected. Its taste is very bitter, but less austere than the powder.
The most beautiful extract of bark, which I have ever seen, was prepared
by Mr. Barry of Plough Court; its colour was that of a deep brilliant
ruby, and its flavour preserved all the characteristic peculiarity of
the recent substance.[499] _Dose_, grs. x to ʒss. Fourteen ounces of the
bark will yield about three ounces and a half of extract. It should be
kept _soft_, so as to be fit for forming pills, and _hard_, so that it
may be reduced to powder.
EXTRACTUM COLOCYNTHIDIS. L. This extract is much milder, although less
powerful, than the pulp; _Dose_, grs. v to ʒss. It soon becomes hard and
mouldy.[500]
EXTRACTUM GENTIANÆ. L.E.D. The bitter principle suffers no deterioration
in the process: it is used principally as a vehicle for metallic
preparations. _Form. 36, 53, 103._ _Dose_, gr. x to ℈j.
EXTRACTUM GLYCYRRHIZÆ. L.D. It is usually imported from Spain; in the
coarser kinds, the pulps of various plums and of prunes are added; it
should dissolve in water without leaving any feculence.[501]
EXTRACTUM HÆMATOXYLI. L.E.D. The astringent properties of the _logwood_
are preserved in the extract, but it becomes so extremely hard, that
pills made of it very commonly pass through the body without undergoing
the least change. _Dose_, grs. x to ʒss dissolved in cinnamon water: it
sometimes imparts a bloody hue to the urine of those who have taken it.
EXTRACTUM HUMULI. L. The bitter taste of the hop characterises this
preparation; whether it possesses, or not, any anodyne properties, seems
very doubtful. _Dose_, grs. v to ℈j.
EXTRACTUM OPII. L.D. As it contains less resinous matter than crude
opium, it is supposed to produce its effects with less subsequent
derangement. See _Opium_. _Dose_, gr. j to v, for an adult.
EXTRACTUM PAPAVERIS. L.D. It is a weak opium. _Dose_, grs. ij to ℈j.
EXTRACTUM SARSAPARILLÆ. Notwithstanding the reputation which this
preparation has acquired, it is very doubtful whether it possesses any
medicinal powers. _Dose_, gr. x to ʒj in pills, or dissolved in the
decoction.
EXTRACTUM STRAMONII. This extract was first recommended by Stöerck, as a
powerful remedy in maniacal affections; its probable value in such
diseases appears to have been suggested by a very curious process of
reasoning, viz. that as it deranged the intellect of the sane, it might
possibly correct that of the insane. Experience has certainly not
confirmed the very sanguine report of Stöerck with regard to its powers,
but it has satisfactorily shewn its occasional value in violent
paroxysms, in quieting the mind, and procuring rest. I am informed by my
friend Dr. Davy, that, for such an object, it has been very frequently
and successfully given, in the Lunatic Military Hospital at Fort
Clarence. He farther states that he has himself made many trials with
the extract of Stramonium, prepared by Mr. Barry (_in vacuo_) as well as
with the common extract; and that he finds the former to be uniformly
more powerful. “In most diseases,” says he, “this medicine would seem
uncertain in its operation, sometimes occasioning an anodyne effect,
and, at other times, producing irritation, and preventing sleep; I have,
however, seen very beneficial effects from it in asthma, and in coughs
that have a nightly exacerbation, in doses of from gr. 1/4 to gr. 2,
daily.”
EXTRACTUM TARAXACI. L.D. The medicinal powers of Dandelion are asserted
to exist unimpaired in this preparation, but it becomes inert by
keeping. See _Taraxacum_. _Dose._ grs. x to ʒj, in combination with
sulphate of potass.