Lead, Red Oxide of. Syn. Red lead, Minium. Prep. This is prepared by exposing unfused protoxide of lead to the air for a long time, at a dull red heat. It is a very heavy powder, of a fine red colour, decomposed by a strong heat into protoxide of lead, and oxygen gas, which is evolved. Somewhat uncertain in its composition, but is generally of the composition Pb3O4 or PbO22PbO. See Red Pigment.
Lead, Dioxide. PbO2. Syn. Biniodide of lead, Peroxide of lead, Puce oxide of lead. Prep. By digesting red oxide of lead in dilute nitric acid; or by infusing a mixture of protoxide of lead and chlorate of potassium at a heat a little below redness, and washing the powdered mass in water; or by transmitting a current of chlorine gas through a solution of neutral acetate of lead. This oxide gives up half its oxygen at a red heat; acids also decompose it. Its chief use is in chemical analysis, to separate sulphurous acid from certain gaseous mixtures, which it converts into sulphuric acid, which it at the same time absorbs, forming sulphate of lead. It has recently been employed as an oxidising agent in the manufacture of the ANILINE DYES.
Lead, Pyrolig′nite of. Sugar of lead made with rough pyroligneous acid. Used in dyeing, chiefly for the preparation of acetate of alumina.
Lead, Sac′charate of. Syn. Plumbi saccharas, L. Prep. (Dr S. E. Hoskins.) Nitric acid, 2 parts; water, 10 parts; mix in a porcelain capsule, add of sugar, 1 part; and apply heat until reaction ceases; then dilute the liquid with distilled water, neutralise it with powdered chalk, filter, and add to the filtrate a solution of acetate of lead, as long as a precipitate (saccharate of lead) forms; lastly, collect the precipitate on a filter, wash and dry it. Used to make nitro-saccharate of lead, and as a source of saccharic acid.
Lead, Sul′phate of. PbSO4. Syn. Plumbi sulphas, L. This salt occurs native in transparent octohedra (lead vitriol), and is obtained in large quantities as a by-product in the preparation of acetate of aluminum for dyeing.
Prep. By adding dilute sulphuric acid to a solution of a soluble salt of lead. It is very sparingly soluble in water and in dilute sulphuric acid, soluble in strong hydrochloric acid and bitartrate of ammonium.
Lead, Sul′phide of. PbS. Syn. Plumbi sulphide. This occurs abundantly in nature in the form of GALENA.
Prep. By fusing metallic lead with sulphur or by passing sulphuretted hydrogen through a solution of a salt of lead.
Lead, Tan′nate of. Syn. Plumbi tannas, L. Prep. Precipitate a solution of acetate of
lead with an infusion of galls, and wash and dry the precipitate. Astringent, sedative, and hæmostatic.—Dose, 1 gr. and upwards, made into a pill. It has been highly recommended in the form of ointment and cataplasms, in bed-sores, chronic ulcers of the feet, white swellings, &c.