This preparation is an acetic solution of the acrid matter of the
Squill, upon which its medicinal efficacy depends.[330] DOSE fʒss to
fʒij. in cinnamon or mint water. See _Scillæ Radix_. FORM. 107, 114.
Alkalies and their carbonates are chemically incompatible with these
_Vinegars_. This preparation, as well as the _Oxymel_, deposites when
long kept a precipitate consisting of _citrate of lime_ and _tannin_,
but its medicinal efficacy is not on that account impaired.
ACIDUM ACETICUM DILUTUM. L. Acidum Acetosum Distillatum. E. Acetum
Distillatum. D.
_Common Distilled Vinegar._
QUALITIES. _Odour_, fainter and less agreeable than common vinegar
(_Acetum_): _Taste_, less acid; _Colour_, none. SPECIFIC GRAVITY; Mr.
Phillips states, that when prepared according to the directions of the
Pharmacopœia, it varies from 1·007 to 1·009; and that 1000 grains of the
latter require for their saturation, 145 grains of crystallized
sub-carbonate of soda. I apprehend, however, that it will be found quite
impossible to obtain a dilute acetic acid equal in strength or specific
gravity, to that last mentioned, by the process of the London
College;[331] it may even be doubted whether it can be produced of the
specific gravity 1·007. The general run of distilled vinegar as found in
the shop of the druggist, varies from 1·005 to 1·006, and contains from
2·80 to 2·826 per cent. of real acid; when of the specific gravity of
1·009 it would contain about 4·73 per cent. Dr. Powell states
(_Translation of the Pharmacop: of London_, 1815) that “one fluid-ounce
ought to dissolve at least thirteen grains of _white marble_;” or, what
is equivalent to it, 39·67 grains of crystallized _Sub-carbonate of
Soda_; acid of this strength corresponds very nearly with six degrees of
the Revenue Acetometer, the proportions being as follow, 100 grains of
Pharmacopœia strength will saturate 8·68 grains of crystallized
_Sub-carbonate of Soda_; 100 grains of acid of 6° of the Acetometer will
saturate 8·70 grains of the salt. CHEMICAL COMPOSITION. Acetic Acid more
largely diluted than that in vinegar, with very minute portions of
uncombined mucilage and extractive. SOLVENT POWERS. It is capable of
dissolving all those vegetable principles which are soluble in water,
and in some cases, as in _Squill_, _Colchicum_, and in several
_Aromatics_ and _Narcotics_, its acid appears to extend its solvent
powers; at the same time it often modifies or diminishes the medicinal
virtues of the substances, as for instance those of _Narcotics_; this
circumstance considerably limits its pharmaceutical application; when
however it is employed, a portion of spirit should be always added, in
order to counteract the spontaneous decomposition to which it is liable,
and the acetic compound should be preserved in stopped bottles. Acetic
acid does not dissolve true resins, but it has some action on gum
resins. MEDICINAL USES. It is refrigerant, and may be advantageously
administered in hemorrhage; especially in cases where the acetate of
lead has been given, since the solubility of this latter substance is
increased by it. See Form. 57; externally, it may be a convenient
adjunct to lotions containing lead. _See Form. 147._ In consequence of
its chemical action upon osseous matter, it has been much employed at
the Gloucester Infirmary to hasten exfoliation of carious bone.
ADULTERATIONS. _Sulphuric Acid_ may be detected by a precipitate being
produced on the addition of acetate of baryta: this test however will
not answer for its detection in common vinegar, for the reason stated
under that article. See _Acetum_. _Sulphurous Acid_ may be recognised by
drawing a little of the vapour into the lungs. The presence of _Nitric
Acid_ may be discovered by saturating the suspected sample with pure
potass, evaporating to dryness, and then treating the product with a
highly concentrated alcohol, the acetate of potass will be thus
dissolved, but as it exerts no action on the _Nitrate_ it will be found
in the residuum, and may be recognised by its deflagration, when thrown
upon burning charcoal;[332] _Copper_ may be detected by the acid
assuming a blue colour, when supersaturated with ammonia; and _Lead_, by
a solution of sulphuretted hydrogen, producing a dark coloured
precipitate. _Tin_ however is the metal with which distilled vinegar is
more usually contaminated, for no vegetable acid will act upon lead
while any tin is present in the mixture, since the latter, being more
oxidable than the former, is exclusively dissolved.