Plaster Of Paris, a preparation of several species of gyp sum, which are obtained principally from Mont Martre, in the vicinity of that city.

The best plaster is hard, white, and somewhat resembles marble : it neither effervesces with aquafortis, nor emits sparks, when stricken against steel; but it is easily calcined in the fire ; and, when pulverized, is of great use for casting statues, forming ceilings, etc.—It pays, on importation, the sum of Is. 2 1/2d. per cwt.—See Alabaster and Gypsum.