Acetate of lead is prepared by the action of vinegar, or other form of dilute acetic acid, either upon plates of metallic lead oxidized by exposure to the air, or directly upon the protoxide of lead with the aid of heat. It is the neutral acetate of the protoxide of lead, consisting of one equivalent of acetic acid, one of protoxide of lead, and three equivalents of water.

Sensible and Chemical Properties. This salt is in the form of shining, white, acicular crystals, isolated or in masses, efflorescent, of a sweet and astringent taste, and often, when long kept, of an acetous odour, owing probably to the action of the carbonic acid of the air, and the slow escape of acetic acid. It is readily dissolved by water; and the solution has a white turbid appearance, which, when the water is free from saline impurities, is removed by the addition of vinegar or acetic acid. The whiteness is owing to the carbonate of lead, formed by the combination of the carbonic acid, which is contained in all natural waters, with a portion of the protoxide of lead, liberating the acetic acid, and thereby giving the solution an acetous smell. In hard waters, the white precipitate is usually a sulphate or chloride of lead, and not redissolved. Distilled water, recently boiled, forms a perfectly clear solution with the acetate, if quite pare; but, as found in the shops, the salt often contains a portion of carbonate, in which case the solution will be more or less opaque.

* In the instances, in the arts, in which water has to pass through leaden pipes, it is recommended by M. Schwartz, of Breslau, that the pipes, before being used, should be filled with a concentrated solution of an alkaline sulphuret, whereby their internal surface receives an insoluble and impermeable varnish of sulphuret of lead, perfectly protecting the water from contact with the metal. (Repertoire de Pharmacia, Nov. 1863.) - Note to the third edition.

Mode of Application. Incompatibles. Acetate of lead yields precipitates with sulphuric, phosphoric, citric, tartaric, meconic, and carbonic acids,* and all the soluble salts of these acids; with hydrochloric and hydriodie acids, and all the soluble chlorides and iodides; with hydrosulphuric acid, and the soluble sulphurets; with tannic acid, and consequently all the vegetable astringents; with certain mucilages, and especially that of slippery elm bark, but not with pure gum; with chondrin and albumen; and with lime-water, and solutions of ammonia, potassa, and soda, the last two redis-solving the precipitate if added in excess. The precipitate formed with the sulphurets is black, with the iodides yellow, and with the other reagents mentioned white or whitish. But, though the above substances are chemically incompatible, it does not follow that they are medicinally so. On the contrary, many of the precipitates are probably not less efficient than the acetate; and, in fact, this salt is often exhibited in connection with substances which decompose it. What it is necessary for the practitioner to guard against is the addition of the incompatible nib-stances in solution. In the form of pill or powder, they may frequently be added with advantage, when rcmedially indicated. The only substances which should always be avoided are sulphuric or hydrosulphuric acid, and the soluble sulphates or sulphurets; as the precipitates formed with these are feeble, if not inert. It is probable that acetate of lead is always decomposed in the alimentary canal, cither by the hydrochloric acid or the chlorides in the stomach, or hydrosulphuric acid in the bowels.