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The thermionic emission from round filaments and flat strips of platinum was measured giving a value for the work function of 5.32 volts and 32 amperes/cm² deg² for the constant A. Highest possible vacuum conditions and heat treatment near 2000^∘{}K were found necessary for obtaining reliable results. The lack of such extreme heat treatment probably accounts for the abnormally high values of the constant A formerly found. Special theoretical explanations for platinum appear no longer necessary.
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Lester V. Whitney (1936) studied this question.
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