File:Selective radiation from various solids. II (1910) (14578582978).jpg

Identifier: sele63013191910131131unse (find matches)
Title: Selective radiation from various solids. II
Year: 1910 (1910s)
Authors:
Subjects: rays and radiation spectra
Publisher: National Bureau of Standards
Contributing Library: NIST Research Library
Digitizing Sponsor: NIST Research Library

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mp bulbs containing theblack filaments were found much hotter than those containingthe silver-gray filaments. He remarks: I have little doubtthat the loss of efficiency when black was due to the energy sup-plied being radiated in large quantities as heat waves from theblackened surfaces, which these surfaces when bright would notemit. Weber 9 showed that the total radiation of the untreatedcarbon was very much greater than the flashed when operated 8 Evans, Proc. Roy. Soc; Feb. 18, 1886. 9 Weber, Phys. Rev., 2, pp. 112 and 197; 1894. Coblentz. Selective Radiation from Solids. 309 90 SO 70 60 50 40 30 20 10 Fig. 6. CYANITE \c a/ \a bf V a : S* 7M 70 60 50 £ 40 30 20 10 h/v Fig. 7ZIRCON aj A \ b 310 Bulletin of the Bureau of Standards. IV01.6.N0.3. 1JJU 140 130 120 b 110 100 Til 90 a J Fig. 8. I TOPAZ >- 80 >(f)m UJ 70 . 1 I 1 XTV« 6050 I f\ 40 !/ / \ - % \ \ 30 \ \ \ \ A c j \a 2010 \i • 1 7/x Cobhntz.) Selective Radiation from Solids. 150 140 311 130 120 no 100 > 80 » 70
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312 Bulletin of the Bureau of Standards. \y0i.6,No.3. under similar conditions. These observations were verified byNichols,10 who investigated the distribution of energy in thespectra of two lamp filaments similar in every respect except that,after they had been flashed, the one was given a thin coating ofcarbon by smoking. The lamps could be brought to incandes-cence separately, but were sealed together in such a manner thatwhatever changes in vacuum occurred in the one would be sharedby the other lamp. He found that the untreated filament emittedmuch more energy in the infra-red than did the treated filamentwhen operated on the same energy input. Continuing this in-quiry as a side issue to the main work on the radiation constantsof metals, the writer n published a series of spectral energy curvesin which the various filaments are set to the same emissivity at agiven wave length, which was taken at 0.7//. The results havingbeen given considerable publicity and the color match12method

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