Liquor Plumbi Diacetatis Dilutus. Lond. Diluted Solution of Diacetate of Lead

"Take solution of diacetate of lead, a fluid drachm and a half; distilled water, a pint; proof spirit, two fluid drachms. Mix."

Plumbi Subacetatis Liquor Compositus, Dub. Compound Solution of Litharge,

The same as the London formula, with double the quantity of each of the ingredients.

This preparation, as an article in the Pharmacopoeia, is superfluous, every surgeon being in the habit of ordering lotions with different proportions of the solution of diacetate of lead, according to the circumstances of the case.

Plumbi Chloridum. Lond. Chloride of Lead

"Take of acetate of lead, nineteen ounces; boiling distilled water, three pints; chloride of sodium, six ounces. Dissolve the acetate of lead and chloride of sodium separately; the former in three pints (namely, the whole) of the distilled water. The liquors being then mixed together, wash what is precipitated with distilled water, when it is cold, and dry it."

1 Nicholson's Journal, xi. 75.

2 Nicholson's Journal, vi. 223.

3 The nature of the salt in this solution was first pointed out by Scheele, who changed a solution of the acetate of lead into Goulard's extract, by keeping it in a plate of lead for the space of a day; but this experiment was overlooked until Dr. Bostock's analysis of the preparation. An excellent mode of preparing it is employed in the French hospitals. Three parts of acetate of lead are dissolved in a sufficient quantity of hot distilled water, and to the solution one part of semi-vitreous oxide of lead is added, in fine powder. The whole is then evaporated until it marks 28° of Beaume's aerometer; and when cold, is filtered. Vide Joum. de Pharm. Dec. 1816, p. 565.

4 Aqua lithargyri acetati composita, P. L. 1787. Liquor Plumbi subacetatis, P. L. 1824.

The acetate of lead and the chloride of sodium are reciprocally decomposed in this process; the acetate of lead parts both with its acid and the oxygen of its oxide: the oxygen uniting with the sodium forms soda, which combines with the acetic acid, whilst the freed chlorine combines with the lead, and forms the chloride.

Qualities. - Chloride of lead is a colourless, fusible salt, soluble in 30 parts of water at 60°, and in 22 at 212°. The latter solution, as it cools, crystallizes in flat, anhydrous crystals, which have generally much brilliancy. Its solubility is augmented by adding a little nitric acid to the water. Its solution is decomposed by the alkalies and their carbonates; and by vegetable astringent infusions and decoctions. It is a compound of 74.3 parts of lead and 25.7 of chlorine in 100 parts; or of 1 eq. of chlorine =35.42 +1 of lead = 103.6, making the equivalent 139.02. (Pb Cl.)

It is merely used for preparing hydrochlorate of morphia. PLUMBI IODIDUM, Lond. Iodide of Lead. "Take of acetate of lead, nine ounces; iodide of potassium, seven ounces; distilled water, one gallon. Dissolve the acetate of lead in six pints of the water, and filter; add to the solution the iodide of potassium dissolved in two pints of the water. Wash what is precipitated, and dry it."

The exchange in this process is reciprocal: the oxygen of the oxide of lead of the acetate passes to the potassium, forming it into potassa, which, uniting with the acetic acid, produces an acetate of potassa, whilst the lead thus freed combines with iodine, also set free, and forms the iodide, which being nearly insoluble in cold water, is precipitated and readily separated from the soluble acetate.

Qualities. - The iodide of lead is a bright golden-yellow coloured powder, when procured by the above process. It is scarcely soluble in water at 60°, but it dissolves readily when boiled in distilled water, and deposits, on cooling, brilliant golden-coloured crystalline scales. It dissolves in solution of pure potassa. It is decomposed by heat, the iodine being dissipated in vapour, and metallic lead left. It is a compound of 1 eq. of lead = 103.6 + of iodine = 126.3, making the equivalent = 229.9. (Pb I.)

Medical properties and uses. - This iodide operates as a deobstruent in glandular obstructions; and, according to

Velpeau, it has removed indolent scrofulous tumours, when iodine and its other compounds have failed. I have had no experience of its value as an internal medicine; but as an external application in aid of the other compounds of iodine internally administered, I have had ample opportunity of ascertaining its efficacy in discussing indolent tumours. I have generally ordered a stronger ointment than that of the Pharmacopoeia, namely, 3jss. of the iodide to j. of lard. The dose of the iodide for internal use is gr. 1/2 to grs. iv.

Plumbi Oxydum Hydratum. Lond. Hydrate of the Oxide of Lead

"Take of solution of diacetate of lead, six pints; distilled water, three gallons; solution of potassa, six pints, or as much as may he required to precipitate the oxide. Mix, and wash the precipitate with water, until nothing alkaline remains."

The oxide in precipitating combines with water, and is thus constituted an insoluble hydrate, whilst the acetate of potassa remains in solution.

Qualities. - Hydrate of oxide of lead is a white powder, insipid and inodorous. As it is soluble in an excess of potassa, it is important, in preparing it, not to employ too much of the alkaline solution. The constituents of the salt are 1 eq. of lead =103.6 + 1 of oxygen = 8, making the equivalents 111.6 (Pb O.) The quantity of water has not yet been determined.

This hydrate is intended for preparing the disulphate of quina.