Crucible
Historical document, translated for reference. It reflects medical knowledge of the 1920s–30s and is not medical advice.
Summary
This article from the 1928–1936 Soviet medical encyclopedia describes the crucible, a vessel used for melting substances at high temperatures. It details the various materials used to make crucibles, including metals, ceramics, and glass, and explains how their properties affect their performance. The text also covers the use of graphite and the limitations of platinum crucibles.
Encyclopedia article (1928–1936)
Crucible is used for melting substances at high temperature. In sale there exist metal crucibles (iron, copper, nickel, silver, platinum, etc.), porcelain, stoneware, quartz, from Pyrex glass and others (Fig. 1, 2). The ability of a crucible made from various clay masses to withstand melting to a certain degree increases with the increase of their porosity. The admixture of graphite increases porosity and also gives the crucible a smooth and shiny surface, to which the molten mass does not adhere; besides, graphite protects the substance being melted (for example, steel) from the oxidizing action of oxygen penetrating into a closed crucible during melting. Crucibles are made of various capacities, usually released for sale with lids. A platinum crucible easily "burns out" if it is held in the reducing part of a gas flame during calcination; platinum crucibles are unsuitable for work with aqua regia and other liquids releasing Cl, P, for molten alkalis, for calcining lead oxide, bismuth, silver, sulfurous substances. See also Gun crucible.
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“Crucible.” Soviet Medical Encyclopedia. English translation of Bolshaya Meditsinskaya Entsiklopediya, 1st ed. (Moscow, 1928–1936), ed. N. A. Semashko. https://sovietmedicalencyclopedia.pages.dev/article/crucible/