The crude element is treated with aqua regia and then evaporated with an excess of hydrochloric acid, the solution diluted and the tellurium precipitated by a current of sulphur dioxide.
Baker this would seem to point to the fact that the tellurium used was insufficiently purified, since his work showed that there was no difference between the first and last fractions (see Chem.
Telluric acid, H2Te04, is obtained in the form of its salts when tellurium is fused with potassium carbonate and nitre, or by the oxidizing action of chlorine on a tellurite in alkaline solution.
An amor phous form is obtained when tellurium is precipitated from its solutions by sulphur dioxide, this variety having a specific gravity 6.015.
Ber., 1886, 94, 560) have found that the rotational coefficient of tellurium is more than fifty times greater than that of bismuth, its sign being positive.
The rare element tellurium has been discovered in New South Wales at Bingara and other parts of the northern districts, as well as at Tarana, on the western line, though at present in such minute quantities as would not repay the cost of working.
The gold is often found in conjunction with tellurium (first discovered in Transylvania in 1782) and is extracted principally at Nagyag, Kapnik-Banya, Zalatna and V6rbspatak.
Like sulphur and selenium, tellurium combines directly with hydrogen to form telluretted hydrogen, TeH2, an extremely objectionable smelling and highly poisonous gas, which was first prepared by Sir H.
Sci., 1909 (iv.), 28, p. 347) claim to have separated two substances (of atomic weights 126.49 and 128.85 respectively) from tellurium, by fractional precipitation of tellurium chloride with water, but in the opinion of H.
The precipitated tellurium is then fused with potassium cyanide, the melt extracted with water and the element precipitated by drawing a current of air through the solution and finally distilled in a current of hydrogen.