S51. Geometrical Theory of Radiating Surfaces with Discussion of Light Tubes. ...Edward P. Hyde Assuming Lambert's cosine law and the inverse square law to apply to infinitesimal surfaces, the errors incident to applying them to finite surfaces are deduced for several simple cases. From a consideration of the case of an infinitely long, uniformly bright strip of finite width a theory of light tubes is developed. (Jan. 15, 1907.) 24 pp. Price, 10 cents. S52. The Influence of Basic Lead Acetate on the Optical ..... .F. J. Bates and J. C. Blake An experimental investigation of the change in the polarization of sucrose produced by the addition of different amounts of basic lead acetate. (Jan. 15, 1907.) 9 pp. Price, 5 cents. $53. On the Colorimetric Determination of Iron with Special Reference to Chemical Reagents.... ..H. N. Stokes and J. R. Cain A method of separating iron from materials in which it exists in minute traces and of determining it colorimetrically as sulphocyanate (Jan. 20, 1907.) 42 pp. Price, 10 cents. $54. On Sulphocyanic Acid..... .H. N. Stokes and J. R. Cain An improved method of preparing sulphocyanic acid, especially for colorimetric iron determinations, with observations on its properties and those of some of its derivatives. (Jan. 20, 1907.) 5 pp. Price, 5 cents. $55. Radiation from and Melting Points of Palladium and Platinum......C. W. Waidner and G. K. Burgess Radiation from platinum by several methods: Measurements of blackbody temperature of iridium furnace at instant of melting of these metals. Melting point on thermoelectric scale. Optical determinations of temperature, using red, green, and blue light, based on Wien's equation for monochromatic radiation. (Mar. 4, 1907.) 46 pp. Price, 10 cents. $56. The Mutual Inductance of a Circle and a Coaxial Single-Layer Coil. The Lorenz Apparatus and the Ayrton-Jones Absolute Electrodynamometer... ..Edward B. Rosa A series formula is developed for calculating the mutual inductance of a circle and a coaxial single-layer coil. The formula is more convenient than one using elliptic integrals and is very accurate. Several examples are given to test and illustrate the formula. (Mar. 1, 1907.) 28 pp. Price, 10 cents. $57. On the Establishment of the Thermodynamic Scale of Temperature by Means of the Constant Pressure Gas Thermometer........Edgar Buckingham A discussion of the methods for finding the thermodynamic corrections of the gas thermometer, together with computations of these corrections for the nitrogen thermometer and comparisons with values given by previous writers. (Feb. 4, 1907.) 57 pp. Price, 15 cents. $58. An Exact Formula for the Mutual Inductance of Coaxial Solenoids.... ..Louis Cohen An exact formula in elliptic integrals is derived for the mutual inductance of two coaxial, concentric single-layer solenoids. (Mar. 14, 1907.) 9 pp. Price, 5 cents. S59. The Mutual Inductance of Coaxial Solenoids... ..E. B. Rosa and Louis Cohen A critical examination of various formulas for calculating the mutual inductance of coaxial solenoids, with numerical examples to test and illustrate the formulas. (Mar. 30, 1907.) 22 pp. Price, io cents. S60. The Production of High Frequency Oscillations S61. An Explanation of the Short Life of Frosted The rapid decrease in candlepower of frosted lamps is due, at least partly, to the increased absorption of the carbon film deposited on the inner side of the bulb. Owing to the diffuse reflection at the frosted surface a relatively large part of the emitted light is compelled to traverse the absorbing carbon film three or more times before finally emerging. Results of confirmatory experiments are given. (Mar. 23, 1907.) 4 pp. Price, 5 cents. S62. Melting Points of the Iron-Group Elements by a New Radiation Method. . . . . Minute quantities of substances melted on platinum ribbon, the temperature of which is measured by means of an optical pyrometer. Method designed for rare substances was tested by determining melting points of Fe, Ni, Co, etc. (Apr. 5, 1907.) 11 pp. Price, 10 cents. $63. On the Determination of the Mean Horizontal Intensity of Incandescent Lamps.. .E. P. Hyde and F. E. Cady A continuation of a previous investigation on this subject. (See reprint No. 43.) Other types of lamps are studied, and the methods and results of similar experiments by Uppenborn are discussed. (Apr. 30, 1907.) 13 pp. Price, 10 cents. S64. The Simultaneous Measurement of the Capacity and Power Factor of Condensers......Frederick W. Grover Four methods for obtaining the ratio of the capacities and the difference of the power factors of two condensers are described and critically compared. Using air condensers as standards, examples are given to show what values of power factor occur in mica and paper condensers by different manufacturers. (May 23, 1907.) 61 pp. Price, 15 cents. $65. A New Determination of the Ratio of the Electromagnetic to the Electrostatic Unit of Electricity... .E. B. Rosa and N. E. Dorsey An extended experimental investigation of the problem, by the method of capacities, employing spherical, cylindrical, and plane condensers. A detailed mathematical discussion of the theory and of sources of error is given. The result, reduced to vacuo, obtained for the ratio of the units is cm Int. 27 2.9971X10 10 sec 2. (The National Physical Laboratory has found (Phil. Trans., 214A, pp. 27-108, 1914) that I international ohm is cm 10 sec 10 000.) (May 20, 1907.) 170 pp. S66. A Comparison of the Various Methods of Determining the Ratio of the Electromagnetic to the Electrostatic Unit of Electricity. Ι E. B. Rosa and N. E. Dorsey A discussion of the relative advantages and disadvantages of the various methods of determining the ratio of the units that have been used or proposed. (June 21, 1907.) 18 pp. Price, 5 cents. S67. Preliminary Specifications for Clark and Weston Standard Cells. . . . . . . . .F. A. Wolff and C. E. Waters Specifications for the construction of Clark and Weston Standard Cells and for the preparation and purification of the materials employed, based in the main on the results obtained in an investigation on the reproducibility and constancy of both types. (See S70.) (Aug. 16, 1907.) 18 pp. Price, 5 cents. $68. Calorimetric Resistance Thermometers and the Transition Temperature of Sodium Sulphate. .H. C. Dickinson and E. F. Mueller Description of platinum resistance thermometers having very small time constant. Calibration on International Hydrogen Scale and application to determination of transition temperature of sodium sulphate. [Superseded by S200.] (June 21, 1907.) 21 pp. Price, 5 cents. S69. On the Standard Scale of Temperature in the In terval 0° to 100°. .C. W. Waidner and H. C. Dickinson Results of intercomparisons of primary standard mercurial thermometers and relation of the temperature scale of the Bureau of Standards to the International Hydrogen Scale of Temperature. The depression and zero recovery of verre dur glass. Description of thermometer comparator, standard barometers, etc. (May 3, 1907.) 66 pp. Price, 20 cents. $70. Clark and Weston Standard Cells... .F. A. Wolff and C. E. Waters An investigation of the accuracy attainable in the reproduction of standards of electromotive force, with detailed descriptions of the purification and preparation of the necessary materials and of the apparatus and methods employed. The results obtained and the close agreement of the Bureau cells with those set up by other investigators establish the suitability of the cell as a fundamental electrical standard. (Sept. 17, 1907.) 80 pp. Price, 20 cents. S71. The Electrode Equilibrium of the Standard Cell.: .F. A. Wolff and C. E. Waters A study of the conditions of equilibrium in both limbs of the cell, made in order to detect possible causes of variation in electromotive force due to secondary chemical reactions which may take place between the ingredients of the cell. (Oct. 4, 1907.) 9 pp. Price, 5 cents. S72. A Comparative Study of Plain and Frosted Lamps. .E. P. Hyde and F. E. Cady The various effects of frosting the bulbs of carbon filament incandescent lamps are studied as changes in (1) absorption, (2) distribution, and (3) life. (1) New lamps show an absorption of only 2 or 3 per cent, which increases rapidly as the lamps burn. (2) The distribution of light around frosted lamps depends on (a) the distribution curve of the bare lamps, and on (b) the shape of the bulb. (3) The theory advanced in a previous paper (see reprint No. 61) to account for the short life of frosted lamps is further substantiated. Readings are given of the temperatures of the bulbs of plain and frosted lamps, both new and old. (July 15, 1907.) 30 pp. $73. On the Variation of Resistances with Atmospheric Humidity. .E. B. Rosa and H. D. Babcock It is shown in this paper that resistances that have been coated with shellac undergo changes in value due to the absorption of moisture by the shellac, and that the resistance increases in a moist atmosphere and decreases in a dry atmosphere. This occurs even if the resistances are kept submerged in oil. A thorough study has been made of resistances of various kinds, and the magnitude of changes occurring and methods of preventing it are given. (Oct. 4, 1907.) 20 pp. Price, 10 cents. $74. On the Self-Inductance of a Toroidal Coil of Rectangular Section... .Edward B. Rosa The simple formula for the self-inductance of such a coil assumes that the current flows in a thin current sheet about the core. Fröhlich's correction formula was derived on the assumption that a winding of round wires is equivalent to a thick current sheet. It is shown in this paper that this assumption leads to a wrong result, and the correct expression is given, enabling the self-inductance to be calculated when the size and spacing of the wires are given. (Aug. 10, 1907.) 7 pp. Price, 5 cents. $75. On the Self-Inductance of Circles ..E. B. Rosa and Louis Cohen It is shown in this paper that some of the formulas that have been given for the self-inductance of circular conductors of circular cross section are incorrect, while the most accurate formulas and the most convenient approximate formulas are indicated and tested by numerical examples. (Aug. 10, 1907.) II pp. Price, 5 cents. S76. The Influence of Frequency on the Resistance and Inductance of Solenoidal Coils.. Louis Cohen A theoretical investigation of the effect of frequency on the resistance and inductance of solenoids. The work of previous investigators is discussed, and it is pointed out that they do not agree with experiment. New formulas are derived which agree with the experimental results of M. Wien, and also with new experiments carried out by the author. (Aug. 16, 1907.) 19 pp. Price, 10 cents. $77. The Atomic Weight of Hydrogen. W. A. Noyes A determination of the ratio of hydrogen to oxygen by direct synthesis of water by the action of hydrogen on copper oxide and by the union of hydrogen and oxygen over palladium foil. (Sept. 11, 1907.) 26 pp. Price, 10 cents. S78. The Best Method of Demagnetizing Iron in Magnetic Testing. ...Charles W. Burrows An experimental investigation to determine a method of freeing iron from previous magnetization preliminary to a permeability test. The influence of the frequency of reversal, the number of reversals, the upper and lower limits of the current, and the method of regulating the demagnetizing current, as well as the influence of eddy currents, temperature, and gentle vibrations, are investigated. A method of procedure for a complete ballistic test is outlined. (Sept. 3, 1907.) 70 pp. Price, 15 cents. $79. A Deflection Potentiometer for Voltmeter Testing ..H. B. Brooks In this paper the theory of the deflection potentiometer is extended (see Paper No. 33 preceding). The instrument is used for the measurement of electromotive force and current by a combination of the null and deflection methods. A second instrument constructed on this plan is described, and a brief outline of the method of design of such instruments is given. [Superseded by S172 and S173.] (Oct. 11, 1907.) 26 pp. Price, 10 cents. S80. The Self and Mutual Inductance of Linear Conductors.. .Edward B. Rosa Formulæ are given for the self and mutual inductance of straight wires, flat strips, and rectangles, for the so-called noninductive arrangement of strips and sheets folded on themselves, and for a "noninductive" winding of wires on a cylinder or in a plane. It is shown how, by the use of geometrical mean distances and arithmetical mean distances and arithmetical mean square distances, certain formulas are derived independently and some approximate formulas made more accurate. (Sept. 15, 1907.) 44 pp. Price, 15 cents. S81. The Atomic Weight of Chlorine . . ...W. A. Noyes and H. C. P. Weber A determination of the atomic weight of chlorine by the direct synthesis of hydrochloric acid by means of hydrogen and potassium chloroplatinate. (Oct. 1, 1907.) 20 pp. Price, 10 cents. S82. The Preparation of Chloroplatinic Acid by Electrolysis of Platinum Black.. ..H. C. P. Weber A method of preparing chloroplatinic acid free from nitric acid by the electrolysis of finely divided platinum in concentrated hydrochloric acid. (Oct. 8, 1907.) 3 pp. Price, 5 cents. S83. The Self-Inductance of a Coil of any Length and any Number of Layers of Wire....Edward B. Rosa The formulas of Weinstein and Stefan for the self-inductance of a circular coil of rectangular section are not accurate for long coils and no other formula yet given is accurate for such cases. In this paper it is shown how to calculate accurately the self-inductance of a coil of any length and any number of layers of wire, taking account also of the corrections depending on the size of the wire and the thickness of the insulation. (Oct. 12, 1907.) 23 pp. Price, 5 cents. S84. The Self-Inductance of a Solenoid of any Number of Layers. .Louis Cohen In this paper is given the derivation of a simple approximate formula for the calculation of the self-inductance of a long coil of any number of layers, and examples are given to illustrate its use. (Oct. 11, 1907.) 8 pp. Price, 5 cents. S85. Instruments and Methods used in Radiometry. .W. W. Coblentz An experimental investigation of sensitivity and relative advantages of the bolometer, radiomicrometer, radiometer, and thermopile, with a review of published data relating to these instruments and to galvanometers of high sensitivity. (Oct. 1, 1907.) 70 pp. Price, 15 cents. S86. A Quartz Compensating Polariscope with Adjustable Sensibility .Frederick Bates The theory and description of a new type of quartz-wedge polariscope which gives the maximum theoretical sensibility, whatever the character of the substance polarized. (Oct. 15, 1907.) 6 pp. Price, 5 cents. S87. An Apparatus for Determining the Wave Form of Magnetic Flux.......M: G. Lloyd and J. V. S. Fisher Gives a description of apparatus by means of which the form factor of an electric wave may be directly determined and waves of magnetic flux or of electric current or voltage plotted. (Nov. 15, 1907.) 10 pp. Price, IO cents. S88. The Effect of Wave Form upon the Iron Losses in .....Morton G. Lloyd This article considers the two elements of core losses in transformers, hysteresis and eddy currents, and the effect of variations of wave form upon them. Assuming the effective voltage to be maintained constant, it is shown that the loss by eddy currents will be constant, while the hysteresis loss varies in a way which can be determined if the form factor of the applied voltage be known. Experimental data are given which substantiate the theoretical results. (Oct. 31, 1907.) 34 Pp. Price, 10 cents. |