Cement, Keene’s Marble

Baked gypsum or plaster of Paris, steeped in a saturated solution of alum, and then recalcined, and reduced to powder. For use it is mixed up with water, as ordinary plaster of Paris. Obs. This cement has been most extensively applied as a stucco. It is susceptible of a high polish, and when coloured produces beautiful imitations of mosaic and other inlaid marbles, scagliola, . It is not adapted to hydraulic purposes, or for exposure to the weather, but it is admirable for internal decorations, and from its extreme hardne is very durable. It may be coloured or tinted of any shade, by diffusing mineral colours (levigated, if in powder) through the water used to mix up the cement with. A pleasing tint is given to this cement by adding a little solution of green copperas to the alum liquor.