$34. Spectrum Lines as Light Sources in Polariscopic Measurements.... .Frederick Bates . . . . A theoretical investigation of errors incidental to the use of a two-line source. An international standard source is advocated and a measurement made of the ratio of the rotation of quartz for this source and the sodium lines. (May 1, 1906.) 11 pp. Price, 10 cents. $35. Polarimetric Sensibility and Accuracy .P. G. Nutting A theoretical investigation of analyzers and light sources for obtaining the highest possible sensibility and accuracy in polarimetry. (May 6, 1906.) 13 pp. $36. On the Platinum Point Electrolytic Detector for Electrical Waves. ...L. W. Austin An experimental study of the platinum-point electrolytic detector, including the sensibility of the detector for electrical waves from a distance as well as from apparatus in the same laboratory. (Mar. 30, 1906.) 15 Pp. Price, 5 cents. $37. Influence of Frequency upon the Self-Inductance of Coils... .J. G. Coffin A mathematical discussion of the variation of the self-inductance of a single layer coil with the frequency of the current. (Mar. 30, 1906.) 23 pp. Price, 10 cents. S38. Experiments on the Heusler Magnetic Alloys... ....K. E. Guthe and L. W. Austin * Experimental study of seven samples of Heusler magnetic alloys, which are made from nonmagnetic metals. The magnetic properties of these samples are given in tables and curves. (Mar. 30, 1906.) 21 pp. Price, IO cents. $39. A Pocket Spectrophotometer... .P. G. Nutting A description of a modified spectrophotometer on the plan of a pocket spectroscope. (July 15, 1906.) 3 pp. Price, 5 cents. $40. Preliminary Measurements on Temperature and Selective Radiation of Incandescent Lamps.. ..C. W. Waidner and G. K. Burgess Measurement of temperature and selective radiation of filaments of tantalum, tungsten, and carbon. On the melting point of tungsten. (Sept. 30, 1906.) 11 pp. Price, 5 cents. S41. Revision of the Formula of Weinstein and Stefan for the Mutual Inductance of Coaxial Coils.. ..Edward B. Rosa Weinstein's formula is accurate only for coils at distances large as compared with the cross section, and Stefan's only at near distances. Weinstein's is revised and corrected, and a new formula derived to replace Stefan's, the two agreeing closely and giving very accurate results. (Sept. 1, 1906.) 27 pp. Price, 5 cents. S42. The Mutual Inductance of Two Circular Coaxial ...E. B. Rosa and Louis Cohen Various formulas for calculating the mutual inductance of coaxial circles and coaxial circular coils of rectangular section are investigated, and some new formulas derived. The best formulas for particular cases are indicated; it is shown where some formulas fail, and numerous examples are given to illustrate the formulas. (Sept. 1, 1906.) 56 pp. Price, 10 cents. S43. On the Determination of the Mean Horizontal Rotating Lamp Method...E. P. Hyde and F. E. Cady A study of the errors incident to this method, due (1) to the distortion of the filament on rotation, and (2) to the inability of the eye to estimate accurately a badly flickering illumination. By the use of a single stationary mirror accurate measurements of mean horizontal candlepower can be made even with badly flickering lamps. (Sept. 1, 1906.) 23 PP. Price, 10 cents. S44. Purity and Intensity of Monochromatic Light A mathematical treatment of spectral impurity and center of luminosity, with the results of an investigation of available light sources. (Sept. 1, 1907.) 18 pp. Price, 5 cents. $45. Radiometric Investigations of Infra-Red Absorption and Reflection Spectra. . . . .W. W. Coblentz The fact that certain groups of elements have characteristic absorption bands is applied to substances containing water of constitution and water of crystallization. It is shown that in the former the oxygen and hydrogen atoms are not united, while in the latter they are united, giving the characteristic absorption spectrum of water. The second part of the paper gives the reflecting power of various metals, not investigated heretofore, and of various minerals, especially of the silicates. (Sept. 1, 1907.) 22 pp. Price, 10 cents. $46. A Vacuum Radiomicrometer .W. W. Coblentz This is a modification of the instrument devised by Boys, and includes also a combination of the Nichols radiometer with the radiomicrometer. The paper indicates directions in which further improvements are possible. (Sept. 15, 1907.) 5 pp. Price, 5 cents. $47. On the Geometrical Mean Distances of Rectangular Areas and the Calculation of Self-Inductance ....Edward B. Rosa It is shown in this paper that Maxwell's correction term in the formula for the self-inductance of a coil of wire, depending on the difference in the mutual inductances of round and square wires, is wrong, and Stefan's only approximately correct. The formulas are fully worked out by the method of geometrical mean distances and verified by other methods, and the true correction term for different cases is calculated. Further use of the method of geometrical mean distances in the calculation of inductances is indicated. (Nov. 1, 1906.) 41 pp. Price, 10 cents. S48. The Compensated Two-Circuit Electrodynamom eter... ..Edward B. Rosa The instrument is used especially for the accurate measurement of alternating current and power. The theory of the instrument is given and a compensation provided so that when calibrated by means of direct current it is correct for alternating currents of different frequencies and any magnitude. (Nov. 1, 1906.) 16 pp. Price, 10 cents. S49. Complete Form of Fechner's Law. P. G. Nutting A mathematical investigation of the quantitative relation between luminous intensity and visual sensation based on König's data on least perceptible increment. (Dec. 15, 1906.) 6 pp. Price, 5 cents. S50. A Comparison of the Unit of Luminous Intensity of the United States with those accurate measurements. Con England, and France...., on which the larger part of the A number of seasoned incander being shown by the deflection of a measured in authoritative laboreded by S172 and S173.] (Mar. 30, 1906.) ratios of the units obtained th generally accepted and with (Jan. 15, 1907.) 16 pp. Pri $51. 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. $52. The Influence of Basic Lead Acetate on the Optical Rotation of Sucrose in Water Solution...... ..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. S56. 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. S58. An Exact Formula for the Mutual Inductance of Coaxial Solenoids... ...Louis Cohen An exact mula in elliptic integrals is derived for the mutual inducous formu, concentric single-layer solenoids. (Mar. 14, 1907.) cles and coaxial circi some new formulas dei. indicated; it is shown where Coaxial Solenoids... are given to illustrate the form...E. B. Rosa and Louis Cohen cents. us formulas for calculating the mutual h numerical examples to test and illus22 pp. Price, io cents. S60. The Production of High Frequency Oscillations from the Electric Arc. ....L. W. Austin An experimental study of the "singing arc" as a source of high frequency oscillations. (Apr. 1, 1907.) 16 pp. Price, 5 cents. 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.. ..G. K. Burgess 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. S63. 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. 2.9971 X10 10 C ]. (The National Physical Laboratory has sec found (Phil. Trans., 214A, pp. 27-108, 1914) that I international ohm is equal to 1.00052 absolute ohms. On the substitution of this value in the above ratio it becomes 2.9979 X 10 The estimated uncertainty is 1 in Price, 20 cents. 10 10 000.) (May 20, 1907.) 170 pp. cm sec S66. A Comparison of the Various Methods of Determining the Ratio of the Electromagnetic to the Electrostatic Unit of Electricity .....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 pro $67. 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. $69. On the Standard Scale of Temperature in the In terval o° 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. $71. 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. S73. 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. |