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Scientific Papers of the Bureau of Standards

Scientific Papers of the Bureau of Standards



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The methods previously applied to the study of critical potentials in the metallic vapours have been, with some modifications, used for the elements P, I, S, N, O, and H. The results obtained are described at length and tabulated. Excepting the case of hydrogen, these elements all show a resonance and ionisation potential similar in relative magnitude to those observed in metallic vapours [see Abs. 1921A00297]. Except for I and S, the actual magnitudes of the potentials are larger than the...
Topic: Table of Contents
Scientific Papers of the Bureau of Standards
by Clark, E.P.
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The author first presents a summary of previous methods of measuring the absolute reflecting powers of surfaces. Nutting's apparatus depended on the principle of infinite parallel planes, and was subject to various inaccuracies. Most of the other devices utilise the integrating sphere. Apparatus. - The new reflectometer devised by the author utilises a sphere with whitened interior, a portion of which can be removed and the surface to be examined substituted. A narrow beam of light can be...
Scientific Papers of the Bureau of Standards
by Jackson, R.F., Silsbee, C.G.
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Scientific Papers of the Bureau of Standards
by Coblentz, W.W., and Hughes, C.W.
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This paper gives data on the ultra-violet reflecting power of the sulphides of metals (lead, molybdenum, iron, and antimony) having a high metallic luster. The materials examined were the natural minerals--galena, molybdenite, pyrites, and stibnite. It is shown that, in contrast with the metals which have a low reflecting power in the ultraviolet and in the visible spectrum, followed by a high reflecting power in the infrared, the sulphides of these metals have a high selective reflection in...
Scientific Papers of the Bureau of Standards
by Bates, Frederick
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Scientific Papers of the Bureau of Standards
by Dorsey, Ernest
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Scientific Papers of the Bureau of Standards
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Describes a new form of vibration galvanometer, which consists of a fine steel wire mounted on one pole of a permanent magnet, and so arranged that the free end may vibrate between the poles of an electromagnet through which the current to be detected passes. The sensitivity, though less than that of instruments of the moving-coil type, is higher than that of other moving-iron instruments, while it possesses the qualities of sturdiness, quick responsiveness, and freedom from the effects of...
Scientific Papers of the Bureau of Standards
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Gives reproductions of photomicrographs to show the value of ammonium persulphate as a revealer of crystalline heterogeneity and chemical inhomogeneity in iron. Various features are revealed by this means which would be missed if other etching agents were employed.
Contains the results derived from a study of the yellow, red, and infra-red regions of the arc spectra of yttrium, lanthanum, and cerium Spectrograms were photographed with the dyes pinacyanol, kryptocyanin, and dicyanin. The rare-earth compounds studied were derived from two sources: From the University of Illinois were obtained the oxalates of yttrium and lanthanum and the oxide of cerium, prepared under the direction of B.S. Hopkins; from Eimer and Amend were obtained the chlorides of...
Topic: Index
Scientific Papers of the Bureau of Standards
by Buckingham, Edgar; Edwards, Junius David
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Scientific Papers of the Bureau of Standards
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Standard Wave lengths in the cadmium spectrum: the wave lengths for 13 lines in the spectrum of tubes containing cadmium vapor aat low pressure are measured relative to the primary standard by means of the Fabry and Perot etalon interferometer. The probable error in most of these values is less than 0.001 A. Constant frequency differences are established which define the separation of subordinate series limits. Evidence that the wave lengths derived spectrum tubes are reproducible is presented.
Scientific Papers of the Bureau of Standards
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A more complete account of the work dealt with in Abs. 1920B00761.;
No lens system gives perfect definition because of the inherent aberrations of spherical refracting surfaces. The aberrations of a centred lens system are denned, and the characteristic manner in which each aberration affects the image is discussed. Methods for the determination of the various aberrations of a photographic objective are described. The Hartmann method, for which a special camera was designed, was used for the measurement of spherical aberration and departure from the sine...
Scientific Papers of the Bureau of Standards
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Scientific Papers of the Bureau of Standards
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Part 1 deals with the materials and construction of various spheres, and describes in detail the construction of a reinforced concrete sphere at the Bureau of Standards. It gives tests of the accuracy of integration by this sphere, the absorption of light by the sphere coating and by objects in the sphere, and the effect of the position of lamps. Proper methods of operation are also outlined. Part 2 gives a fairly complete resume of the general theory of the sphere, with the addition of a...
Topic: Table of Contents
Scientific Papers of the Bureau of Standards
by Lowell, P.D.
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Electron tube amplifiers may make use of either radio frequency amplification or audio frequency amplification, or both. Radio-frequency amplification consists in the amplification of the received radio-frequency current before it is detected. The use of radio-frequency amplification makes it possible to receive a very weak signal which cannot be heard at all if only audio frequency amplification is used. The coil antennas used in direction finding work receive only a very feeble signal, and...
For several years the Bureau of Standards has been conducting tests and measurements of the characteristics of photographic light-sensitive materials. The ultimate object of the investigation is to standardize methods and the necessary conditions for testing these materials. At the present time workers in this field are using different standards, with the result that the data obtained are not directly comparable. It is hoped that this work will lead to the standardization that is so much needed.
Scientific Papers of the Bureau of Standards
by Souder, W.; Hidnert, P.
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Thermal expansion data are given for 28 specimens of iron and steel, most of which were heated above 900°C. The expansion of iron was determined over the range 25° to 945°C. The expansion from 25° to 100°C. was found to be 12.0×10/sup -6/. The average expansion of a number of steels, over this same range, was found to be 11.2×10/sup -6/, and for the range 25° to 600°C., 14.2×10/sup -6/. The coefficient for the ordinary steels was approximately 23×10/sup -6/. The shrinkages and...
Scientific Papers of the Bureau of Standards
by Coblentz, W.W.
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Scientific Papers of the Bureau of Standards
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Describes the preparation of different alloys of aluminium with magnesium and zinc. All these alloys were found to tarnish in time, so that they could not be used for permanent mirrors. The best in this respect was the compound Al/sub 3/Mg/sub 4/, and for this alloy a reflectivity of 92% was obtained at 0.7 ?. The zinc alloy was found to have a minimum reflectivity at 0.9 ? and a similar minimum was found for pure zinc at 1 ?.
Topic: Index
In the present investigation the specific volume of saturated ammonia vapour was measured in the temperature interval - 50 degrees to 50 degrees C. by two methods - one involving a direct determination of the mass of the vapour contained in a known volume, and the other, an optical method, involving measurements of the index of refraction of the vapour. In the case of the first method the effect of adsorption was studied and found to be of a magnitude comparable with the limit of accuracy of...
The ordinary hermetically sealed Clark cell is subject to two types of failure: the cracking of the glass near the amalgam, and the interruption of the circuit by the gradual formation of gas in the amalgam limb. The cracking of the glass has long been known to be due to the alloying of the amalgam with the Pt wire and a resultant increase in the diam. of the wire. The trouble may be largely overcome by employing platinum wire which has previously been subjected for a short time to the action...
This paper gives data on the linear thermal expansion of 4 samples of aluminum and 51 samples of important aluminum alloys. The preparation, chemical composition, heat treatment, etc., are included. Most of the specimens were examined from room temperature to about 500 degrees Celsius. Typical expansion curves of the various groups of samples are shown and discussed.
Gives the results of experiments on the thermal expansion of three different classes of insulating materials: porcelain, marble, and the phenol condensation products (bakelite, condensite, formica, etc.). The method employed is described and illustrated in the paper. The expansion coefficients of 40 samples of various kinds of porcelain were found to vary over a wide range, from 1.6 to 19.6 millionths per 1 deg. C. The expansion curves of most materials are concave, but with porcelain both...
The international system of secondary standards extends to 6750 A . in the red, but no extensive interferometer comparisons have been made between the primary standard and longer wave-lengths of iron. New values are given for 161 lines between 5534.525 A . and 8824.238 A ., of which 75 are longer than 6750 A . The probable error of each value is of the order of 0.001 A . In the region in which these determinations overlap the secondary standards there is a systematic deviation indicating, that...
Interference methods are described by which the planeness and parallelism errors of precision surfaces can be measured and the length of standard gauges determined by direct comparison with the standard light waves with an uncertainty of not more than a few millionths of an inch. The errors of other gauges can be determined by comparison with these calibrated standards with equal precision.
Scientific Papers of the Bureau of Standards
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The arc spectra of gadolinium and dysprosium were measured from lambda 5500 to approximately lambda 9000, using spectrograms prepared by the author and also by Eder. The sources were gadolinium oxide and dysprosium oxalate. Most of the lines are faint, and several suggest band-heads. The lines given amount to 950 for Gd, and 800 lines for Dy.
Scientific Papers of the Bureau of Standards
by Meggers, W.F., Walters, Jr., F.M.
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Scientific Papers of the Bureau of Standards
by Merica, P.D.; Waltenberg, R.G.; Scott, H.
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In the spring of 1916 an investigation of some of the forms of gas-detectors in use was begun by the Bureau of Standards. None of the existing forms of apparatus was found suitable for all purposes, and the investigation has led to the design of several new forms, which are more reliable than the old ones or better adapted to certain specific uses. All the new devices described depend upon the combustion of the gas contained in the surrounding atmosphere at the surface of an electrically heated...
Topic: Index
Scientific Papers of the Bureau of Standards
by Freeman, Jr., J.R., Sillers, Jr., F., Brandt, P.F.
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One of the most useful and at the same time least commonly used methods of thermal analysis for the determination of transformations in metals and alloys consists in the recording of the time intervals required for successive increments of temperature-change during heating or cooling, the temperature of the furnace which contains the specimen being altered at a uniform rate. For the measurement of the successive time intervals it is usual to employ a chronograph, the observer subsequently...
Scientific Papers of the Bureau of Standards
by Meggers, W.F.
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Gives the values of 50 wave-lengths in the spectrum of argon, 18 of krypton and 12 of xenon, obtained by comparison with the international primary standard by means of étalon interferometers. The error is considered to be of the order of 0.001 Å. in most cases. From wave-length measurements in argon and krypton frequency differences are obtained which are constant within the probable error of the measurements, thus giving further confirmation of the Combination Principle of Ritz. As the heavy...
The effect of Mn as a hardening element in carbon steels, as distinct from its deoxidant and desulphurising effects, is studied in an extensive series of alloys, in conjunction with their corresponding microstructures. Steels containing 0-1.6% C. and 0.2% Mn, annealed and normalised, are included. The effect of Mn is described as a "restraining" influence, pearlite having, even after annealing, a fine-grained sorbitic structure, such as results ordinarily upon -more rapid cooling....
Scientific Papers of the Bureau of Standards
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The work described in this paper was undertaken for the purpose of satisfying an increasing demand for accurate data on the thermal expansion of molybdenum.
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Topic: Table of Contents
Scientific Papers of the Bureau of Standards
by Pienkowsky, A.T.
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Continuing, their systematic investigation of spectra in the red and infra-red regions [Abs. 1918A01160], the authors have made careful measurements of wave-lengths of lines in the spectra of titanium, vanadium, chromium, manganese, molybdenum, tungsten, and uranium. The concave-grating spectrograph of the Bureau of Standards was used to photograph the yellow, red, and infra-red arc spectra of these elements, the plates used being sensitised to the red and infra-red rays with pinacyanol and...
Scientific Papers of the Bureau of Standards
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Scientific Papers of the Bureau of Standards
by Dryden, H.L., Hill, G.C.
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Scientific Papers of the Bureau of Standards
by Rawdon, Henry S., Berglund, T.
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Scientific Papers of the Bureau of Standards
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These measurements form a portion of the work undertaken by the Bureau of Standards in the determination of the thermal properties of materials used as refrigerating media. The existing data on the vapour-pressure-temperature relation for ammonia are undoubtedly sufficiently accurate to meet the requirements of refrigeration engineering. The Clapeyron equation, however, offers a means of correlating the measurements of the latent heat of vaporisation [see Abs. 1918A00278] with the data on...
Scientific Papers of the Bureau of Standards
by Sanford, R.L., Cheney, W.L., Barry, J.M.
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The pressure gage- a number of quartz plates suitably cut are arranged condenser fashion in a stack and introduced in an electric circuit. The quartz plates are subjected to the gas pressure to be measured by means of a piston. The combination of these constitutes a gage which is screwed into the wall of the gas chamber and the leads are brought out through holes drilled through the wall. The rec ording galvanometer- a ballistic galvanometer whose period is long compared to the duration of the...
Scientific Papers of the Bureau of Standards
by Clark, E.P.
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Contains the results of an investigation during which the Brinell hardness was determined for five steels varying in carbon content from 0.07 to 1.12% after heat treatment arranged to produce wide variations in grain size. Upon heating for 6-hour periods no very appreciable increase in grain size occurs until the Ac transformation has occurred. The change in grain size often appears to be a very abrupt one, taking place within a narrow range of temperature. Two methods were used for obtaining...
Scientific Papers of the Bureau of Standards
by Mueller, E.F.; Burgess, H.A.
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The sulphur boiling point occupies a position of unusual importance among the thermometric fixed points on account of the care and accuracy with which its temperature has been determined, the precision with which this temperature may be reproduced, but most of all on account of the very general practice of using it to determine one of the fundamental calibration constants of the platinum resistance thermometer, which serves as the most precise and convenient means now available for defining the...