INFUSUM ARMORACIÆ COMPOSITUM. L. In this preparation the stimulant
property of the horse-radish is materially aided by the mustard; pure
alkalies, but not their carbonates, may form extemporaneous additions;
for the other incompatibles, see _Armoraciæ Radix_. Dose, f℥iss. _Form.
45._
INFUSUM AURANTII COMPOSITUM. L. A grateful stomachic, having the
agreeable compound taste of its several ingredients; it has the merit of
sitting easily on the stomach. Dose, f℥j-f℥iss.
INFUSUM CATECHU COMPOSITUM. L.E. This infusion is a powerful astringent,
rendered grateful by the addition of cinnamon; it will keep for several
months, provided the directions of the Edinburgh College be not followed
in adding the syrup. In prescribing it, we must remember that it
contains a large proportion of _tannin_. See _Catechu_. Dose, f℥j-f℥iij.
INFUSUM GENTIANÆ COMPOSITUM. L. An elegant tonic and stomachic infusion.
It affords a good example of the virtues of a natural substance being
enhanced by the additions of art, as discussed at page 164, for the
bitterness of the gentian is here subdued by the aromatic quality of the
lemon and orange peel. _Incompatibles._ _Acetate of lead_ throws down a
copious precipitate from the infusion, and _sulphate of iron_ strikes a
brown colour, but no precipitate takes place for several hours.
INFUSUM ROSÆ COMPOSITUM. L.E.D. This is an infusion of the petals of the
red rose, rendered astringent and refrigerant,[538] by the addition of
dilute sulphuric acid. By referring to the DYNAMETER, it will be seen
that f℥j; does not contain more than four and a half minims of _dilute_
acid, which are equivalent to three-sevenths of a minim of the strong
_concentrated_ acid. Wherever therefore we expect any advantage from
this latter ingredient, the quantity must be increased by extemporaneous
addition. _Incompatibles._ All those bodies which are decomposed by the
sulphuric acid; the _sulphates of iron_ and _zinc_ do not immediately
alter the infusion, but they _slowly_ decompose it, producing
precipitates of a dark colour. Dr. Clarke of Cambridge detected _iron_
in the petals;[539] may not the presence of this metal enhance the tonic
powers of the infusion? It affords a most elegant vehicle for the
exhibition of cathartic salts.
INFUSUM SENNÆ COMPOSITUM. L.E.D. A pint of water will take up the active
matter of ℥j of senna, but nothing beyond that proportion; hence there
is an unnecessary waste in the London process. The quantity of infusion
directed to be made at one time, is also injudicious, since by simple
exposure to the air for only a few hours, in consequence of the powerful
affinity of its extractive matter for oxygen, a yellow precipitate takes
place, and the infusion loses its purgative quality, and excites
_tormina_ in the bowels; in preparing it therefore, we see the necessity
of conducting the process in _covered_ vessels, and of making only such
a portion as may be required for immediate use; indeed, notwithstanding
every precaution, the extractive will to a certain extent become
oxidized, and the infusion have a tendency to gripe.[540] Dr. Cullen
used to say that Senna was one of the best purgatives, if it could only
be divested of its griping quality; this however he was unable to
obviate, because he was not aware of its cause, and therefore conjoined
it with various aromatics, instead of those salts[541] which might be
capable of increasing the solubility of its oxidized extractive, or the
purgative activity of the infusion; see page 150, and 161. _Soluble
tartar_ and _alkaline salts_ are its most useful adjuncts; it is however
rarely prescribed in practice without the addition of other cathartics.
(_Form. 70, 76, 90._) Sydenham’s favourite “_potio cathartica
lenitiva_,” consisted of an infusion of tamarinds, senna leaves, and
rhubarb, with the addition of manna and syrup of roses. The addition of
tamarinds renders the infusion more grateful but less active; when made
with _bohea tea_, it is in a great degree deprived of its nauseous
taste; a decoction of guaiacum increases its powers, and is said at the
same time to render it milder. Bitters also very considerably exalt its
efficacy, see page 153. A pint of the infusion with a drachm of jalap
forms an excellent combination for a purgative enema. _Incompatibles._
The infusion is disturbed by _strong acids_; _lime water_; _nitrate of
silver_; _oxy-muriate of mercury_; _acetate of lead_; _tartarized
antimony_; and by an _infusion of yellow cinchona_. DOSE, f℥j-f℥ij.