THE USE OF POTASSIUM TELLURITE IN DIFFERENTIAL MEDIA

Abstract

The chemical and pharmacological properties of tellurium have long been a matter of interest to investigators. Early work groups tellurium and the closely related substance, selenium, with arsenic and antimony in their effect on the mammalian organism. These substances belong to the intermediate group of elements, which are capable of functioning as bases or as non-metals. Tellurium, like selenium, when it is a base, is usually bivalent (H2Te), but in tellurious acid it is tetravalent (H2TeO3), and in telluric acid, hexavalent (H2TeO4). A resemblance can be seen to the similar compounds of sulphur, to which tellurium and selenium are closely related chemically and physically. Gies, and Mead and Gies, in 1901, reviewed earlier work and discussed the physiological and toxicological effects of tellurium in detail. They found that tellurites were readily reduced to metallic tellurium by living protoplasm, and that granular deposits of the metal were widely found in the tissues of animals killed by the administration of toxic doses of tellurite. Knop (1885) and Bokorny (1893) found that sprouting maize, algae and infusoria are uninjured by concentrations of potassium tellurite as low as 0.1 per cent. Jones (1909), in a study of sele-nite, found that heated tissue does not lose its ability to reduce the salt, and concluded that the active agent was a reducing sugar. He demonstrated in titro, that glucose and related reducing substances readily caused the precipitation of metallic selenium at 35°C. and higher temperatures.