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Spectrophotoelectrical sensitivity of bournonite and pyrargyrite
824
U. S. BUREAU OF STANDARDS NOTES.
[J.F.I.
low as 30 kilocycles (10,000 metres). This amplifier has also been found effective for the reception of undamped waves, ~vhcn used with a separate heterodyne. The use of a loud-speaking telephone receiver such as the “ Magnavox ” was made possible by applying to the field coil of the loud-speaker an alternating current rectified by a “ Tungar ” rectifier tube. The impedence of the field coil was sufficient to smooth out the pulsating current to such an extent that the hum was not annoying. It was also advantageous to couple the loudspeaking reproducer circuit to the plate circuit of the last amplifier tube by means of a one-to-one ratio telephone transformer with a 0.02 microfarad condenser in series with the telephone circuit. SPECTROPHOTOELECTRICAL SENSITIVITY BOURNONITE AND PYRARGYRITE.
OF
By W. W. Coblentz and J. F. Eckford. [ABSTRACT.]
THE present paper, considered in connection with previously published data on proustite (Bureau of Standards Scientific Papers, No. 412), represents a study of the effect of chemical constitution upon spectrophotoelectrical sensitivity. Experimental data are given on the effect of temperature and of the intensity of the radiation stimulus upon the photoelectrical sensitivity of the minerals bournonite and pyrargyrite, in the spectral region extending from 0.3~ in the ultra-violet to 2/* in the infra-red. The spectrophotoelectrical reaction curve of bournonite is entirely different from that of the constituent sulphides of copper and lead (which are not photo-sensitive) and of antimony which has its photoelectrical sensitivity confined principally to a band at 0.77~ in the extreme red. On the other hand, bournonite has a high spectrophotoelectrical sensitivity extending from the extreme violet to IP in the infra-red, with two wide, ill-defined maxima in the region of 0.55~” and o.gsp respectively. On lowering the temperature the intrinsic spectrophotoelectrical sensitivity of bournonite is greatly increased and the maxima shift towards the short wave-lengths. The maximum in the violet usually remains the more intense at the lowest temperatures. ’ Scirrltific Pnpcrs. No. 451,
Dec., 1922.1
U.
S. Bc-REAU
OF STI\SD_~RTJS SOTES.
825
The spectrophotoelectrical reaction of the mineral pyrargyrite, which is a double sulphide of silver and antimony, is entirely different from that of the constituent sulphides of silver and of antimony, which also exhibit photosensitivity. At 22O C. the photoelectrical reaction of pyrargyrite consists of a wide unsymmetrical maximum in the ultra-violet, with a weak, ill-defined maximum in the region of 0.63~. At low temperatures, - 165” C., pyrargyrite reacts electrically to radiations of all wave-lengths extending from the extreme ultra-violet to 1.5~ in the infra-red; but the greatest photoelectrical reaction is localized in the band at 0.63~. There is a great similarity in the spectrophotoelectrical and chemical properties of pyrargyrite (silver-antimony sulphide) and of proustite (silver-arsenic sulphide). In a general way, the foregoing properties of photoelectrical reaction spectra are analagous to properties of absorption spectra, as affected by chemical constitution, from which it appears that perhaps ultimately the two phenomena may be traced to a common source lvithin the molecule. THE PREPARATION OF IRON-CARBON-MANGANESE AND THE EFFECTS OF CARBON AND MANGANESE MECHANICAL PROPERTIES OF IRON.’
ALLOYS ON THE
By R. P. Neville and J. R. Cain. [ABSTRACT.]
paper describes of a series of very
THIS
erties
the preparation and mechanical proppure alloys of electrolytic iron, carbon,
and manganese, whose compositions were so chosen as to bring out the specific effects on pure iron of : ( I ) additions of carbon; (r) additions of manganese; and, (3) additions of carbon and The maximanganese together in varying relative proportions. mum amount each of carbon and manganese in each series was o per cent., or pure iron. about 1.5 per cent . ; the minimum, The alloys were made in three-pound ingots by melting electrolytic iron in an electric vacuum furnace, in a crucible of pure magnesia, to which the carbon and manganese were added after fusion of the iron. From these ingots tensile test specimens were made and tested in the annealed condition. ’Scientific
Papers,
No. 453.
U. S. BUREAU OF STANDARDS NOTES.
[J.F.I.
low as 30 kilocycles (10,000 metres). This amplifier has also been found effective for the reception of undamped waves, ~vhcn used with a separate heterodyne. The use of a loud-speaking telephone receiver such as the “ Magnavox ” was made possible by applying to the field coil of the loud-speaker an alternating current rectified by a “ Tungar ” rectifier tube. The impedence of the field coil was sufficient to smooth out the pulsating current to such an extent that the hum was not annoying. It was also advantageous to couple the loudspeaking reproducer circuit to the plate circuit of the last amplifier tube by means of a one-to-one ratio telephone transformer with a 0.02 microfarad condenser in series with the telephone circuit. SPECTROPHOTOELECTRICAL SENSITIVITY BOURNONITE AND PYRARGYRITE.
OF
By W. W. Coblentz and J. F. Eckford. [ABSTRACT.]
THE present paper, considered in connection with previously published data on proustite (Bureau of Standards Scientific Papers, No. 412), represents a study of the effect of chemical constitution upon spectrophotoelectrical sensitivity. Experimental data are given on the effect of temperature and of the intensity of the radiation stimulus upon the photoelectrical sensitivity of the minerals bournonite and pyrargyrite, in the spectral region extending from 0.3~ in the ultra-violet to 2/* in the infra-red. The spectrophotoelectrical reaction curve of bournonite is entirely different from that of the constituent sulphides of copper and lead (which are not photo-sensitive) and of antimony which has its photoelectrical sensitivity confined principally to a band at 0.77~ in the extreme red. On the other hand, bournonite has a high spectrophotoelectrical sensitivity extending from the extreme violet to IP in the infra-red, with two wide, ill-defined maxima in the region of 0.55~” and o.gsp respectively. On lowering the temperature the intrinsic spectrophotoelectrical sensitivity of bournonite is greatly increased and the maxima shift towards the short wave-lengths. The maximum in the violet usually remains the more intense at the lowest temperatures. ’ Scirrltific Pnpcrs. No. 451,
Dec., 1922.1
U.
S. Bc-REAU
OF STI\SD_~RTJS SOTES.
825
The spectrophotoelectrical reaction of the mineral pyrargyrite, which is a double sulphide of silver and antimony, is entirely different from that of the constituent sulphides of silver and of antimony, which also exhibit photosensitivity. At 22O C. the photoelectrical reaction of pyrargyrite consists of a wide unsymmetrical maximum in the ultra-violet, with a weak, ill-defined maximum in the region of 0.63~. At low temperatures, - 165” C., pyrargyrite reacts electrically to radiations of all wave-lengths extending from the extreme ultra-violet to 1.5~ in the infra-red; but the greatest photoelectrical reaction is localized in the band at 0.63~. There is a great similarity in the spectrophotoelectrical and chemical properties of pyrargyrite (silver-antimony sulphide) and of proustite (silver-arsenic sulphide). In a general way, the foregoing properties of photoelectrical reaction spectra are analagous to properties of absorption spectra, as affected by chemical constitution, from which it appears that perhaps ultimately the two phenomena may be traced to a common source lvithin the molecule. THE PREPARATION OF IRON-CARBON-MANGANESE AND THE EFFECTS OF CARBON AND MANGANESE MECHANICAL PROPERTIES OF IRON.’
ALLOYS ON THE
By R. P. Neville and J. R. Cain. [ABSTRACT.]
paper describes of a series of very
THIS
erties
the preparation and mechanical proppure alloys of electrolytic iron, carbon,
and manganese, whose compositions were so chosen as to bring out the specific effects on pure iron of : ( I ) additions of carbon; (r) additions of manganese; and, (3) additions of carbon and The maximanganese together in varying relative proportions. mum amount each of carbon and manganese in each series was o per cent., or pure iron. about 1.5 per cent . ; the minimum, The alloys were made in three-pound ingots by melting electrolytic iron in an electric vacuum furnace, in a crucible of pure magnesia, to which the carbon and manganese were added after fusion of the iron. From these ingots tensile test specimens were made and tested in the annealed condition. ’Scientific
Papers,
No. 453.