Emery-Wheel

Wheel for grinding or polishing made of emery crystals cemented together by some suitable material to form a matrix for them. Such materials are feldspar, celluloid, japan varnish, glue, and silica, the requirements being that the cement shall not glaze, but yet shall be strong enough to hold the particles together. These wheels turn at high velocities, usually having a peripheral speed of ab. 3,500 feet per minute. They are specially used for fine tool-grinding, since their velocity enables them to be used very thin and of just the shape or section which is needed. For true work in hardened steel also the emery-wheel is better than a natural stone. It is much used in foundries for finishing castings. Emetics. Medicines which cause vomiting. Emeu, or EMU. See CURSORES ( Ratita ).