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The ultra-violet and visible transmission of various colored glasses
U. S. BUREAU OF STANDARDS NOTES.
242
[J. F. I.
conclusion arrived at is that, if corrections are made for atmospheric absorption, the value recently obtained at Na,ples is close to the average value, viz., 0 = 5.7 In the second part of the paper, the present status of the constant of spectral radiation is discussed.
THE
ULTRA-VIOLET AND VISIBLE TRANSMISSION VARIOUS COLORED GLASSES. By K. S. Gibson,
E. P. T. Tyndall,
and H.
OF
J. McNicholas.
[ABSTRACT.]
DURING the last three years the spectral transmissions of a great! number and variety of glasses have been measured by the Bureau of Standards throughout the ultra-violet, visible, and infra-red. The transmissions throughout the infra-red, and extending into the visible, have already been published,* as well as the transmissions for the visible and ultra-violet of glasses particularly classed as eye-protective.+ In the present paper are given the transmissions for the visible and ultra-violet of 87 samples, of glass, representing over jo different kinds, mostly colored, which are not used primarily for eye-protection, but which are useful for various other special purposes. The glasses listed in this and the other papers mentioned, are representative of what may be obtained to-day on the American market, and include also some of foreign make which were obtainable before the war. It is thus possible to compare the relative merits of foreign a,nd American glass, and see in what respect the latter may duplicate or improve upon the former. All of the glasses of this paper, so far as it was possible to get values, were measured photographically and visually, and in most cases photoelectrically. The photographic (Hilger sector photometer with quartz spectograph) method may be used from BTechnologic Paper No. 148. Coblentz and Emerson: B. S. Tech. Paper No. 93, May, 1917; 3rd edition, February, 1919. Coblentz, Emerson, and Long: B. S. Sci’. Paper No. 325, August, 1918. t Gibson and McNicholas : B. S. Tech. Paper No. 119, June, 1919. *
U.
I’ek)., ~20.1
S. EURE_\U
OF ST~SWRDS
NOTES.
243
230 to 500 millimicrons, the photoelectric (null method) from spectrophotometer) 380 to 600, and the visual ( Koenig-Zvlartens The data are presented in the form of transfrom 436 to 720. mission curves extending from 720 millicrons throughout the visible and ultra-violet as far as the specimens have any appreciable The methods overlap to such an extent that when transmission. all are used extremely reliable curves may be obtained. With possibly a few exceptions, therefoere, the curves as given in this paper are considered accurate within 6.02 on the transmission scale of 0.00 to 1.00, and in many ca,ses, especially at low transmissions and in the better specimens, the uncertainty is less than this. For each specimen are given the transmission curve, the thickIn ness, the trade name or designation, and the maker or deal’er. each figure also is given the relative visibility curve for the average human eye. An inspection of the curves must be made by those interested, inasmuch as this kind of data cannot be summarized, Various practical uses to which these glasses are put are indicated, such as ultra-violet signaling, railway signaling, improvement of visibility both for visual and photographic work, Of special value protection of the eyes, and selective ray filters. in scientific wojrk is their use as filters to obtain monochromatic light from the mercury, helium, or hydrogen lamps. Transmission curves omfsuch filters are given.
NOTES
ON
THE MICROSTRUCTURE OF IRON STEEL AT HIGH TEMPERATURE.’ By Henry
S. Rawdon
and Howard
AND
MILD
Scott.
[ABSTRACT.]
THE microstructure of iron and mild steel which prevails at The high temperatures was studied by means of “hea,t-etching.” polished specimens were heated in vacua to the desired temperature; volatilization of the metal from the surface is sufficient, tlogether with the volume changes in the critical transformation, to produce an etched pattern on the previously polished face which ’ Scientific
Paper
No.
356.
242
[J. F. I.
conclusion arrived at is that, if corrections are made for atmospheric absorption, the value recently obtained at Na,ples is close to the average value, viz., 0 = 5.7 In the second part of the paper, the present status of the constant of spectral radiation is discussed.
THE
ULTRA-VIOLET AND VISIBLE TRANSMISSION VARIOUS COLORED GLASSES. By K. S. Gibson,
E. P. T. Tyndall,
and H.
OF
J. McNicholas.
[ABSTRACT.]
DURING the last three years the spectral transmissions of a great! number and variety of glasses have been measured by the Bureau of Standards throughout the ultra-violet, visible, and infra-red. The transmissions throughout the infra-red, and extending into the visible, have already been published,* as well as the transmissions for the visible and ultra-violet of glasses particularly classed as eye-protective.+ In the present paper are given the transmissions for the visible and ultra-violet of 87 samples, of glass, representing over jo different kinds, mostly colored, which are not used primarily for eye-protection, but which are useful for various other special purposes. The glasses listed in this and the other papers mentioned, are representative of what may be obtained to-day on the American market, and include also some of foreign make which were obtainable before the war. It is thus possible to compare the relative merits of foreign a,nd American glass, and see in what respect the latter may duplicate or improve upon the former. All of the glasses of this paper, so far as it was possible to get values, were measured photographically and visually, and in most cases photoelectrically. The photographic (Hilger sector photometer with quartz spectograph) method may be used from BTechnologic Paper No. 148. Coblentz and Emerson: B. S. Tech. Paper No. 93, May, 1917; 3rd edition, February, 1919. Coblentz, Emerson, and Long: B. S. Sci’. Paper No. 325, August, 1918. t Gibson and McNicholas : B. S. Tech. Paper No. 119, June, 1919. *
U.
I’ek)., ~20.1
S. EURE_\U
OF ST~SWRDS
NOTES.
243
230 to 500 millimicrons, the photoelectric (null method) from spectrophotometer) 380 to 600, and the visual ( Koenig-Zvlartens The data are presented in the form of transfrom 436 to 720. mission curves extending from 720 millicrons throughout the visible and ultra-violet as far as the specimens have any appreciable The methods overlap to such an extent that when transmission. all are used extremely reliable curves may be obtained. With possibly a few exceptions, therefoere, the curves as given in this paper are considered accurate within 6.02 on the transmission scale of 0.00 to 1.00, and in many ca,ses, especially at low transmissions and in the better specimens, the uncertainty is less than this. For each specimen are given the transmission curve, the thickIn ness, the trade name or designation, and the maker or deal’er. each figure also is given the relative visibility curve for the average human eye. An inspection of the curves must be made by those interested, inasmuch as this kind of data cannot be summarized, Various practical uses to which these glasses are put are indicated, such as ultra-violet signaling, railway signaling, improvement of visibility both for visual and photographic work, Of special value protection of the eyes, and selective ray filters. in scientific wojrk is their use as filters to obtain monochromatic light from the mercury, helium, or hydrogen lamps. Transmission curves omfsuch filters are given.
NOTES
ON
THE MICROSTRUCTURE OF IRON STEEL AT HIGH TEMPERATURE.’ By Henry
S. Rawdon
and Howard
AND
MILD
Scott.
[ABSTRACT.]
THE microstructure of iron and mild steel which prevails at The high temperatures was studied by means of “hea,t-etching.” polished specimens were heated in vacua to the desired temperature; volatilization of the metal from the surface is sufficient, tlogether with the volume changes in the critical transformation, to produce an etched pattern on the previously polished face which ’ Scientific
Paper
No.
356.