ACETIS HYDRARGYRI. E. Acetas Hydrargyri. D. _Acetate of Mercury._
QUALITIES. _Form_, small flaky crystals; _Colour_, silvery white; _Taste_, acrid. CHEMICAL COMPOSITION. Acetic Acid, and Oxyd of Mercury. SOLUBILITY. It is soluble in hot, but very sparingly in cold water, and quite insoluble in Alcohol. FORMS OF EXHIBITION. It should be always given in pills,[323] it is however seldom used. DOSE, gr. j. As an external application, a solution of it, in the proportion of grs. j. to f℥i of rose water, has been commended as a cosmetic.
QUALITIES. _Taste_, grateful, austere and acidulous. CHEMICAL COMPOSITION. All its qualities depend upon the presence of _Super-oxalate of Potass_. In France the plant is commonly cultivated for the use of the table.
The qualities of this plant, like those of the preceding, depend upon _Super-oxalate of Potass_.
QUALITIES. Too well known to require description.[324] CHYMICAL COMPOSITION. Acetic acid largely diluted with water, vegetable gluten, mucilage, sugar, extractive matter, and frequently malic and tartaric acids, together with small proportions of sulphate of lime, sulphate of potass, and alcohol. Its composition however varies according to the fermented liquor from which it is obtained:[325] e. g. wine yields a paler, purer, and stronger acid than fermented malt liquors or solutions of sugar, hence the superiority of that prepared in France and Italy. Vinegar is liable to spontaneous decomposition, or to become mouldy, and consequently for the purposes of pharmacy it should be distilled; as however the change depends upon the presence of gluten, it may if boiled be kept for a much longer time, and if powdered _animal_[326] charcoal be previously added, it will become quite colourless like distilled vinegar, and that without being impaired in strength, whereas it always becomes much weaker by distillation. It is a curious circumstance that this is the only vegetable acid, except the _Prussic_, that rises in distillation in combination with water.
ADULTERATIONS. Sulphuric acid, as it does not produce any turbid appearance in vinegar, is generally the acid selected for sharpening it; but it must be remembered, that the maker is allowed by law, to mix one thousandth of its weight of Sulphuric acid[327] with it; so that the _muriate of baryta_ when added to such vinegar may be expected to produce 1⅕ grain of insoluble _sulphate_ in every fluid-ounce; if a more considerable quantity of precipitate occurs, we may infer that an excessive proportion of sulphuric acid is present; although some allowance ought perhaps to be made for the presence of the sulphates of potass and lime, which are always contained in vinegar. Of this vinegar 1000 grains should saturate 148 grains of crystallized sub-carbonate of soda; a fluid-ounce of the same, 68–3/4 grains.[328] For the purpose of making the vinegar appear stronger, acrid vegetables, as _grains of Paradise_, _berries of Spurge Flax_, _Capsicum_, _Pellitory of Spain_, &c. are sometimes infused in it, but by tasting it with attention, the pungency of such substances may be easily detected. For the other adulterations, see _Acidum Aceticum_.