Plumbi Acetas. Lond. Acetate of Lead

"Take of oxide of lead, rubbed to powder, four pounds and two ounces; acetic acid, distilled water, each four pints. Mix the acid with the water, and add the oxide of lead to them, and dissolve it with a gentle heat; then filter. Lastly, evaporate the solution, that crystals may form."

Acetas Plumbi, Edin. Acetate of Lead.

"Take of white oxide of lead, any quantity; weaker acetic acid, a sufficient quantity. Put the oxide into a cucurbit, and pour over it ten times its weight of the acid. Let the mixture

1 The empirical nostrum, sold under the name of Dalby's Carminative consists of carbonate of magnesia, Э ij., oil of peppermint j., oil of nutmeg ij., oil of aniseed, iij., tincture of castor xxx., tincture of assafoetida xv., spirit of pennyroyal xv., compound tincture of cardamoms xxx., and peppermint water f 3 ij.

2 Saccharum Saturni, P. L. 1720-45. Cerussa acetata, P. L. 1787. Plumbi superacetas, P. L. 1809.

stand upon a warm sand bath until the acid become sweet; then let this be poured off, and add fresh portions of acid successively until no more sweetness is communicated. Evaporate all the fluid, freed from impurities, in a glass vessel, to the consistence of thin honey, and set it aside in a cold place, that crystals may form, which are to be dried in the shade. Evaporate again the residuary liquor, that new crystals may be obtained; and repeat the evaporation until no more are formed."

Plumbi Acetas, Dub. Acetate of Lead.

"Take of carbonate of lead, called Cerussa, any quantity; distilled vinegar, ten times its weight. Digest them in a glass vessel until the vinegar become sweet; and having poured this off, add more until it cease to become sweet. Filter the solution, and crystallize by alternate slow evaporation and cooling. Dry the crystals in the shade."

Syn. Acetate de Plomb crystallise (F.), Essigsaures Blei (G.), Zucchero di Saturno (I.).

In the London process the acetic acid unites with the oxide after evaporation; and the salt crystallizes in the form of an acetate. But on account of the expense of the process, the preparation of this salt is seldom undertaken by the apothecary. The acetate (sugar of lead), usually found in the shops, which is manufactured on a large scale for the use of the calico printers, is purified. It is chiefly prepared in Holland, in the following manner: - Sheets of lead, coiled up, are put into pots, in which they are half immersed in distilled vinegar, and digested a sufficient time: the upper half, or that which is not immersed, is covered with an efflorescence of carbonate of lead, after which it is immersed in the vinegar, and the part which was before immersed is now brought up to be converted into carbonate as before, when the plate is again turned; and this is repeated many times, until the vinegar become milky. This solution is next boiled in tinned vessels down to about one third of the original quantity, then strained, and the salt crystallized by slow cooling.

The crystals obtained by a second evaporation of the mother-water are brown and deliquescent1; and the whole requires to be again dissolved in rain or distilled water, and recrystallized.

Qualities. - This salt, when pure, is inodorous, has a sweet, astringent taste, and crystallizes in white, glossy, oblique-angled'2 six sided prisms, which are generally aggregated into irregular masses. Its specific gravity is 2.35.3 Acetate of lead slightly effloresces: it is soluble in 25 parts of distilled water, either hot or cold; but after standing for some time, a slight decomposition takes place, and a small portion of white powder is deposited, which is an insoluble carbonate. It is also soluble in alcohol. In pump or hard water, which always contains carbonic acid, it is instantly decomposed, forming a milky solution, and a copious precipitate falls; it is also decomposed by the alkalies and their carbonates, most of the acids and neutral salts, lime and its salts, magnesia and its carbonate and sulphate, and all the sulphurets; but it is not affected by a solution of gum. The constituents of 100 parts are 58.9 of oxide of lead, 26.8 of acid, and 14.3 of water1; or of 1 eq. of oxide of lead = 111.6 +1 of acetic acid = 51.48+3 of water=27; making the equivalent 190.08 (Pb A.)

1 Aikin's Dictionary of Chymistry, ii. 26.

2 Phillips's Trans, of the Pharm. 1824.

3 Hassenfratz.

Medical properties and uses, - Taken internally, acetate of lead is a very powerful sedative astringent. It is a valuable remedy in pulmonary, uterine, and intestinal haemorrhages; in restraining which it has a very powerful influence. Combining it with opium is supposed to prevent the deleterious effects which salts of lead are apt to produce when taken into the stomach; but this is an erroneous opinion. It is more advantageously administered with diluted distilled vinegar, to prevent its change into the carbonate, which renders it poisonous. Some years ago, Dr. Hildebrand, of Lemberg, tried this salt in combination with opium, with seeming advantage, in phthisis; and it has been since occasionally used in this country; but, as far as I have observed, it is not likely to be generally employed by British practitioners. Dissolved in a large proportion of water, with a small quantity of distilled vinegar to prevent decomposition, it forms an excellent collyrium in ophthalmia; and somewhat less diluted, its solution is in common use as an external application in superficial inflammation.

Objections have, nevertheless, been raised to the long-continued external use of the preparations of lead; but the daily extensive employment of them in this form, without any bad effects, is a sufficient proof that, if they occasionally have produced mischief, it is to be attributed to the chance of their change into the carbonate, which is the only direct poison among the salts of lead.

The dose of acetate of lead, when internally exhibited, is from grs. iij, to grs. x., given every six or eight hours. It may be made into a pill with crumb of bread, with or without opium, according to the circumstances of the case. As a collyrium or lotion, the proportions may be from grs. x. to

1 Phillips's Trans, of the Pharm. 1824.

Э j. of the salt in f viij. of distilled water. In every instan ce in which this salt causes colica pictonum it is converted into carbonate of lead, which, as I have already said, is the only poisonous salt of lead : thence the addition of distilled vinegar is necessary to prevent decomposition; and this is also requisite on the same account in prescribing it as a lotion when distilled water is not employed. Many practitioners object even to the external application of salts of lead; but I have used them extensively, and have never found any bad effects to result from them, except in fermenting poultices, in which they are changed into the carbonate. (For the mode of counteracting these bad effects, see Plumbi Carbonas, Part II.)

Officinal preparations. - Ceratum Plumbi Acetatis, L. Liquor Plumbi diacetatis, L.