Prep. Often made by exposing sheets of metallic lead to the fumes of acetic and carbonic acids, from vinegar and spent tan.

Prop. & Comp. A heavy white powder insoluble in water, blackened by sulphuretted hydrogen. It is soluble with effervescence in dilute nitric acid, forming a solution which is precipitatcd yellow by iodide of potassium, and white by sulphuric acid; it dissolves entirely in acetic acid; the solution treated with sulphuretted hydrogen in excess, boiled and filtered, gives no precipitate with oxalate of ammonia. The composition of this salt is represented by the formula, 2 (Pb O, Co2) + Pb O, HO.

Off. Prep. Unguentum Plumbi Carbonatis. Ointment of Carbonate of Lead. (Carbonate of lead, in powder, sixty-four grains; simple ointment, one ounce). [Carbonate of lead in very fine powder, eighty grains; ointment of lard, a troy ounce. U. S.]

Therapeutics. This salt is not used as an internal remedy; when applied externally, it acts as a local astringent and sedative, and may be used in the same cases as the subacetate. It may be employed either alone or mixed with starch, and powdered upon diseased surfaces; or it may be applied in the form of the ointment.