4103. Iodide of Lead

4103.    Iodide of Lead. Acetate of lead, 9 ounces; water, 6 pints; dissolve; iodide of potassium (pure), 7 ounces; water, 2pints; dissolve. Add the latter solution to the former, wash and dry the precipitate, and keep it from the light. Or: Iodide of potassium and nitate of lead, of each 1 ounce; dissolve each separately in 3/4 pint of water, mix, collect the precipitate in a muslin or linen filter, and wash it with water; then boil it in 3 gallons water, soured with pyroligneous (acetic) acid, 3 fluid ounces; let the solution settle (still keeping the liquid near the boiling point), and decant the clear; as tho water cools, the iodide will subside in brilliant golden yellow lamellae, or minute crystals.

The latter is the best process, as any adhering oxide of lead is dissolved out by the acid. (Cooley).

4104. Chromate of Lead

4104.    Chromate of Lead. To a filtered solution of acetate or nitrate of lead, add a filtered solution of chromate of potassa, as long as a precipitate forms, which is collected, washed with water, and dried. This forms chrome-yellow. (See No. 2705 (Chrome Yellow).)

4105. Dichromate of Lead

4105.    Dichromate of Lead. Boil pure carbonate of lead with chromate of potassa in excess, until it assumes a proper red color; then wash it with pure water, and dry it in the shade. This is the pigment known as chrome-red. (See No. 2706 (Chrome Red).)

4106. Litharge

4106.    Litharge. Litharge is an oxide of lead prepared by scraping off the dross that forms on the surface of melted lead exposed to a current of air (dross of lead), and heating it to a full red, to melt out any undecomposed metal. The fused oxide in cooling forms a yellow or reddish semi-crystalline mass, which readily separates into scales; these, when ground, constitute the powdered litharge of commerce. Litharge is also prepared by exposing red lead to a heat sufficiently high to fuse it, and English litharge is obtained as a secondary product by liquefaction, from argentiferous lead ore. Tho litharge of commerce is distinguished by its color into litharge of gold, which is dark colored and impure, and litharge of silver, which is purer, and paler colored. The dark color of the former is chiefly owing to the presence of red lead. In grinding litharge, about 1 pound of olive oil is usually added to each 1 cwt., to prevent dust. Litharge is employed in pharmacy, to make plasters and several other preparations of lead; by painters as a dryer for oils, and for various other purposes in the arts.

4107. Nitrate of Lead

4107.    Nitrate of Lead. Litharge, 41/2 ounces; diluted nitric acid, 1 pint; dissolve by a gentle heat, and set the solution aside to crystallize. Employed as external application in cutaneous affections, etc.. A very weak solution is an excellent remedy for chapped hands, etc..