The Oyster; a common, bivalvous, marine shell fish.

The shell of the oyster, levigated into a subtile powder, is employed as an absorbent, in heart-burns and other like complaints arising from acidities in the first passages: the hollow shells are generally made choice of, as containing more, than the thinner flat ones, of the fine white earth, in proportion to the outer rough coat, which last is found to be considerably impregnated impregnated with sea salt. By calcination, they are converted into a strong quicklime, which imparts to water a greater degree of lithontriptic power than the mineral limes; see Calx viva.

(a) A more particular account of this soffil may be seen in Neumann's chemical works, p. I I. and the Memoires de l' academic royale des sciences de Berlin, pour l'ann. 1748.

Teftae oftre-orumprepar,. Ph. Lond.