“A very simple experiment shows that a black surface is a better radiator, or pours out more energy when hot, than a surface which does not absorb fully, but reflects much of the radiation which falls upon it. If a platinum foil with some black marks on it be heated to redness, the marks, black when cold, are much brighter than the surrounding metal when hot; they are, in fact, pouring out much more visible radiation than the metal.”

—  John Henry Poynting

[Smithsonian Report for 1904, 185–193, Radiation in the solar system, https://books.google.com/books?id=2G1xpr2w4PUC&pg=PA186] (p. 185)

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John Henry Poynting2
physicist 1852–1914

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