A Dictionary of Arts: Chalk.

A Dictionary of Arts, Manufactures, and Mines; containing A Clear Exposition of Their Principles and Practice

by Andrew Ure, M. D.;
F. R. S. M. G. S. Lond.: M. Acad. M. S. Philad.; S. PH. DOC. N. GERM. Ranow.; Mulh. Etc. Etc.

Illustrated with nearly fifteen hundred engravings on wood
Eleventh American, From The Last London Edition.
To which is appended, a Supplement of Recent Improvements to The Present Time.

New York: D Appleton & company, 200 Broadway. Philadelphia: George S. Appleton, 148 Chestnut St.
MDCCCXLVII

1847

CHALK. (Craie, Fr. Kreide, Germ.) A friable carbonate of lime, white, opaque, soft, dull, or without any appearance of polish in its fracture. Its specific gravity varies from 2.4 to 2.6. It usually contains a little silica, alumina, and oxyde of iron. It may be purified by trituration and elutriation. The silicious and ferrugious matters subside first, and the finer chalky particles floating in the supernatant liquid, may be decanted with it, and obtained by subsidence. When thus purified, it is called whitening, and Spanish white, in England; schlemmkreide, in Germany; blanc de Troyes, and blanc de Meudon, in France. Pure chalk should dissolve readily in dilute muriatic acid, and the solution should afford no precipitate with water of ammonia.

BLACK CHALK. A mineral, called also drawing-slate.

FRENCH CHALK. Steatite, or soap-stone; a soft magnesian mineral.

RED CHALK. A clay coloured with the peroxyde of iron, of which it contains about 17 per cent.