Plaster, Warm. See Calefacient plaster, Burgundy pitch p., &c.
Plaster of Wax. Syn. Simple plaster; Emplastrum attrahens, E. simplex (Ph. E.), E. ceræ, L. Prep. 1. (Ph. E.) Beeswax, 3 oz.; suet and yellow resin, of each 2 oz.; melt them together, and stir the mixture briskly until it concretes by cooling.
2. (Ph. L. 1836.) Yellow wax and suet, of each 3 lbs.; yellow resin, 1 lb.; as the last. Intended to be employed as a simple dressing, especially to blistered surfaces. It is now seldom used.
Plaster, White Diach′ylon. See Plaster of Lead.
Plaster, Yellow Diach′ylon. See Plaster of Galbanum.
Plaster, Zinco-lead. Syn. Emplastrum zinco-plumbicum, E. Diapompholygos, L. Prep. (Ph. Suec.) Beeswax, 1 lb; olive oil and graphite (black lead), of each 6 oz.; carbonate of lead, 4 oz.; oxide of zinc (impure), 3 oz.; olibanum, 11⁄2 oz.; boil to a plaster. Astringent and desiccant. Other forms substitute an equal weight of litharge for the graphite.
PLATE. The name is commonly given to gold and silver wrought into instruments or utensils for domestic use.
The cleaning of plate is an important operation in a large establishment, as its durability, and much of its beauty, depend on this being properly done. The common practice of using mercurial plate powder is destructive to both of these, as mercury not only rapidly erodes the surface of silver, but renders it soft, and, in extreme cases, even brittle. The only powder that may be safely used for silver is prepared chalk, of the best quality. For gold, the form of red oxide of iron, known as Jeweller’s Rouge, is the most useful and appropriate.
In his ‘Workshop Receipts’ Mr Spon recommends the following:—“Take an ounce each of cream of tartar, common salt, and alum, and boil in a gallon or more of water. After the plate is taken out and rubbed dry it puts on a beautiful silvery whiteness. Powdered magnesia may be used dry for articles slightly tarnished, but if very dirty it must be used first wet and then dry.”
Chamois leather, a plate brush, or very soft woollen rags, should alone be used to apply them; and their application should be gentle and long continued, rather than the reverse. Dirty plate, after being cleaned with boiling water, may be restored by boiling it in water, each quart of which contains a few grains of carbonate of soda, and about an ounce of prepared chalk, calcined hartshorn, or cuttle-fish bone, in very fine powder. The ebullition sets up a gentle friction, which effects its purpose admirably. The boiled plate, after