Liquor Plumbi Diacetatis. Lond. Solution of Diacetate of Lead

"Take of acetate of lead, two pounds and three ounces; oxide of lead, rubbed to powder, one pound and four ounces; distilled water, six pints. Boil them for half an hour, assiduously stirring; and when the solution is cold, add as much distilled water as is sufficient to measure with it six pints. Lastly, strain the solution."

Plumbi Subacetatis Liquor, Dub. Solution of Subacetate of Lead.

"Take of semivitreous oxide of lead, one part; distilled vinegar, twelve parts. Put them into a glass vessel, and boil, assiduously stirring until eleven parts only of the fluid remain; then set the solution aside, and strain it after the faeces have subsided."

Syn. Acetate de Plomb liquide (F.), Blaiwasser (G.), Aceto di Saturno (I.).

In the process of the London College, the acetate yields up a portion of its acid to the oxide of lead, by which means it becomes a diacetate. The proportion of litharge ordered in the Dublin formula is too large, a gallon of distilled vinegar of the specific gravity 1.007 being capable of dissolving ten ounces only of the oxide; but the preparation varies according to the strength of the vinegar.

Qualities. - This solution of diacetate of lead, when properly prepared, is of a pale straw colour, has a slight acetous odour, and an austere, somewhat sweetish taste. It is partially decomposed when largely diluted with distilled water; and with pump water a heavy precipitate instantly takes places: it is also precipitated in the form of a white subsalt by the alkalies and their carbonates; and a black precipitate is produced by sulphuretted hydrogen and the alkaline sulphurets.

1 Aqua lythargyri acetati, P. L. 1787. Liquor Plumbi acetatis, P. L. 1809. Liquor Plumbi subacetatis, P. L. 1824.

It is, indeed, the best test for detecting sulphuretted hydrogen in any compound. The quantity of sulphur is always 2/15 of the sulphuret of lead, to which, if we add 1/15, we obtain the weight of the sulphuretted hydrogen. This solution is also incompatible with solutions of mucilage of gum, which it coagulates; and, indeed, it is the most delicate test for mucilage with which we are acquainted. According to the experiments of Dr. Bostock1, the constituents of 100 parts of the saturated solution are 23.1 of oxide of lead, 5 of acetic acid, and 71.9 of water, which agree with the statement of The-nard2, who found that the salt, when crystallized, consists of 17 parts of acid, 78 of oxide of lead, and 5 of water, in 100 parts.3 In equivalents, it consists of 1 eq. of acetic acid = 51.48 + 2 eq. of protoxide of lead = 222.12; making the equivalent 273.60. (Pb2A.)

Medical properties and uses. - This solution is used only externally, and when diluted with distilled water forms a very useful, cooling, discutient application to phlegmonous inflammations and burns. It was introduced into practice by M. Goulard, a surgeon of Montpelier; and thence its appellation of Goulard's Extract.