Characteristics and applications of selenium-rectifier cells

The rectification properties of selenium cells were first discovered in the year 1883. C. T. Fritts described them in the American Journal of Science.
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However, they were never used to any extent, except possibly as photocells. After the introduction of the copper-oxide rectifier, research activities were stimulated, and selenium cells were again rediscovered. The first commercial cells were made in Germany in the early 30's, and, as the technique of manufacture improved, better cells were made with better life expectancy. The General Electric Company, after a period of developmental activity, started to make cells in 1938, first in its research laboratories, and subsequently a manufacturing plant was set up which permits producing cells in large quantities within relatively close electrical tolerances. This paper contains data pertaining to these cells particularly, and the information may not apply in detail to cells manufactured by other methods without some correction factors.