Common Sorrel Leaves.
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.
ACETOSELLA. L. Oxalis Acetosella.
Wood Sorrel.
The qualities of this plant, like those of the preceding, depend upon Super-oxalate of Potass.
ACETUM. L. Vinegar.
Acidum Acetosum, E. Acetum Vini. D.
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.
The purest vinegar which I have ever examined is that manufactured from malt, by Mr. Mackintosh of Glasgow. The strongest malt vinegar is termed proof vinegar, and is called by the manufacturer No. 24; it is estimated to contain 4·73 per cent. of real acetic acid.[[329]] Its strength in relation to the other forms of acetic acid, will be seen by referring to the Medicinal Dynameter, and to the table inserted under the article Acidum Aceticum Fortius. In the former Editions of this work it was stated, that a Vinegar had of late years appeared in the market produced from the distillation of wood, (Pyroligneous Acid.) This article has now come into very general use; and the manufacturers have at length succeeded in divesting it of that empyreumatic flavour which had so long rendered it objectionable. See Acidum Aceticum Fortius e Ligno destillatum.