seleniumn.
/sɪˈliːnɪəm/ Chemistry.
One of the rarer elements, closely resembling tellurium in properties, and, like that element, formerly classed among the metals, but now regarded as non-metallic. Symbol Se; atomic weight 79.Like sulphur, to which it is in many respects analogous, it has several allotropic forms; one of these, still sometimes known as metallic selenium, is a dark grey or black solid with metallic lustre.An important property of selenium is that its electrical resistance is greatly decreased by exposure to light: hence its use in the photophone or radiophone of A. Graham Bell.
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selenium1818
1818 tr. J. J. Berzelius in Ann. Philos. 11 292 The analogy of tellurium has induced me to give it the name of selenium.
1818 W. Henry Elements Exper. Chem. (ed. 8) II. i. xix. 162 Selenium has a gray colour, and a very brilliant metallic lustre.
1849 D. Campbell Pract. Text-bk. Inorg. Chem. 61 Selenium when distilled is of a reddish-brown colour, when reduced to powder it is red; when fused in a mass, it is of a lead grey colour and metallic lustre.
1881 A. G. Bell Sound by Radiant Energy 23 But the selenium was very inconstant in its action.
Compounds
selenium cell n. a photoconductive or photovoltaic cell containing selenium.
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1880 A. G. Bell in Jrnl. Franklin Inst. Oct. 243 The resistance of selenium cells employed by former experimenters was measured in millions of ohms.
1929 N. R. Campbell & D. Ritchie Photoelectric Cells i. 1 Selenium cells might be termed photo-conductive.
1946 Nature 20 July 88/1 In the early days of his training he [sc. J. L. Baird] devised an improved pattern of selenium cell, which led him to develop a crude form of television.
1977 J. Hedgecoe Photographer's Handbk. 32 Your meter may use a selenium cell which generates a minute current of electricity, measured on a galvanometer.
selenium eye n. (see quot. 1893).
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1893 T. O'C. Sloane Standard Electr. Dict. 478 Selenium eye, a model eye in which selenium in circuit with a battery and galvanometer takes the place of the retina of the human eye.
This entry has not yet been fully updated (first published 1911; most recently modified version published online December 2019).
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