Crucibles

Crucibles are vessels employed for exposing substances to high temperature, either for purposes of fusion, or to induce some chemical or physical change. They should, therefore, be capable of withstanding great heat and changes of temperature, and should also be unacted upon by the fuel, or the substances heated. Clay crucibles are made of very refractory fire-clays, or mixtures of clay and sand, and various sands, as Hessian, Cornish, London, Stourbridge, etc., are used in assaying and metallurgy. Porcelain and platinum crucibles are indispensable to the chemist in quantitative analysis. Silver, nickel, iron, plumbago, and lime crucibles are also each used in special operations for which the other materials would be unsuitable.