File:Selective radiation from various solids (1908) (14583707477).jpg

Identifier: select515919119089797unse (find matches)
Title: Selective radiation from various solids
Year: 1908 (1900s)
Authors:
Subjects: rays and radiation light reflection spectra
Publisher: National Bureau of Standards
Contributing Library: NIST Research Library
Digitizing Sponsor: NIST Research Library

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ve just mentioned. But it seems more probable that this isdue to the rapid growth of the general emission of the inter^^eningfrequencies which, with a doubtful broadening of the emissionband (see figs, i and 2), obliterates the selective emission at hightemperatures. In Fig. 13 are given a series of isochromatics fora iio-volt Xernst glower 1.4 cm long and 1.4 mm in diameter.The current was supplied from a 2000-volt 600-watt transformeron a iio-volt circuit. The supply of energy was regulated bymeans of resistances in the primary. The voltage was obtainedwith a multiple-cell electrostatic voltmeter. The cur\^es (not cor-rected for slit-width and bolometer sensibility) for the mostintense part of the spectrum pass through a slight double cur\^a-ture, thus giving them the general outline of that of platinum.The normal burning is 80 watts and above that point the isochro-matics appear to show a slight increase in cur^ature. The inter- 184 BMlletin of the Bureau of Standards. (Voi.s,no.2.
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90 WATTS Cobieyitz?\ ScIcctivc Radiatioji fvoDi )^arioiis Solids. 185 section of the graphs for wave lengths X= 1.206 /x and X= 1.633 l^at 73 watts (somewhat greater if sHt-width correction is appHed)shows that the maximum of the spectral energy cur\e, for thispower consumption, lies between these two points, as previouslyobser^^ed. This method of locating the maximum eliminates thecorrection for slit width, and is an independent proof of the pre-vious obser\^ations that the maximum of the energy curvx fornormal burning (80 watts) does not lie at such short wave lengthsas was obserAcd by previous investigators. This of course is onthe assumption that the glowers were of the same material (seecurve 6, Fig. 8, for other substances), the base of which is zirco-nium oxide with a small percentage of cerium, thorium., or yttriumoxide. 3. Isochromatics of oligoclase.—In Xo. 35, p. 318, of CarnegiePublications, it was shown that in the case of vacuum tube radia-tion the intensity of the emi

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