U.S. Bureau of Standards

E.B. Rasa, B. McCollom, O.S. Peters, Electrolysis in Concrete, U.S. Bureau of Standards, Technological Paper No. 18, Washington 1913. 

Figure 12-24A. Mollier chart for properties of ammonia. (Used by permission Dept, of Commerce, U.S. Bureau of Standards.)...

The different processes and their material requirements are reviewed in References 19 and 20, while annual conferences have been held under the auspices of the U.S. Bureau of Standards and other interested bodies since 1976. The processes involved embrace combustion, gasification and liquefaction, each of which presents characteristically different corrosive environments. 

William Frederick Meggers. Physicist at the U. S. Bureau of Standards since 1914. Chief of die spectroscopy section. Author of many papers on optics, astrophysics, photography, measurement of wave-length standards, and description and analysis of spectra. The instrument in the foreground is a concave grating spectrograph, used for photographing the emission spectrum of rhenium (41). 

The values of Huggins are probably, the most accurate lattice energies obtainable and agree with the Born-Haber cycle values to within the experimental accuracy of the cycle terms. The values given by the Kapustinskii equation will be seen to be rather low. The Bom cycle values are obtained from the values of AH/ M+(g) and aH/ MX(s) given by the U. S. Bureau of Standards, circular 500, and the values of AH/ X (g) decided upon by Pritchard 108), as a result of a review of all the experimental data. 

Later workers have used the Born-Mayer equation and the extended Mayer-Huggins method, allowing for the Van der Waals and zero-point energies. The computations made and their comparison with thermochemical data, utilizing the most recent data, either from the U. S. Bureau of Standards Circular 500 or from later sources, will be considered below. 

In the case of Hg, the transition 2HgX HgzXa must be considered and in the case of indium and gallium the disproportionation to the trihalide will be considered. It is interesting to note in passing that the value A/7/ InCl = 41 kcal/mole is quite close to the thermochemical value quoted in the U. S. Bureau of Standards, circular 500. The enthalpies of disproportionation are given in Table XXXVIII. The conclusions that... 

This Third Edition is the third major U.S. compendium on thermochemical properties to be published in SI units with a standard-state pressure of 1 bar (0.1 MPa). The other two publications originated with the U.S. Bureau of Standards and the U.S. Geological Survey. ... 

There appears to be no relation between the amount of material separated and the current used and the separations are hence not governed by Faraday s law Tech. Paper 51, U. S. Bureau of Standards, Washington, 1915). 

C. O. Fairchild. M. S. U. S. Bureau of Standards. Pyrometry and Thermometry. F. W. Faragher. Ph. D. Fellow, Mellon Institute of Industrial Research. Fractional Distillation. 

Paul D. Foote. Ph. D. Physicist, U. S. Bureau of Standards. Pyrometry and Thermometry. 

Investigators who wish to check their measurement techniques against those of a standardizing laboratory can buy a sample of silicon powder from the U.S. Bureau of Standards. These samples, known as Standard Reference Material 640, were made available in 1974 [11.8]. The Bureau states the weighted average of the lattice parameter of this material to be 5.43088 A, with an estimated standard error of 3.5 X 10 A. 

Compiled at the U. S. Bureau of Standards. This table is based upon true specific gravity instead of apparent. For concentration of 25% by volume the apparent specific gravity is 0.96872, the true specific gravity 0.96876. For lower concentration the difference between the two specific gravities is less for higher concentration it is relatively greater. 

Comprehensive tables have been published in International Tables of the Fluid State, Pergamon Press. See also the compilations of the U.S. Bureau of Standards. 

Ann. Phys.y 1876, clviii, 71 William Francis Hillebrand (Honolulu, 12 December 1853-Washington, 7 February 1925) studied with Bunsen (Ph.D. Heidelberg 1876), was chemist for the U.S. Geological Survey (1880-1908) and chief chemist for the U.S. Bureau of Standards (1908-25). He and T. H. Norton in Bunsen s laboratory prepared cerium, lanthanum, and didymium by electrolysis Ann. Phys.y 1875, civ, 683 1875, clvi, 466. 

In a preceding paragraph we have described the heat of a reaction as the amount of heat evolved or absorbed when the reaction takes place at constant temperature and pressure. Two mutually contradictory definitions of heat of reactions are used at the present time in textbooks and reference books. For over a century it has been customary to define the heat of a reaction (heat of combustion, heat of formation, heat of solution) as the heat evolved in the process that is, as —AH°. On the other hand, heats of fusion and vaporization have been defined as the heat absorbed during fusion or vaporization. During the last few years many chemists have adopted the definition of heat of reaction as the heat absorbed in the process. This usage is to be found, for example, in the valuable reference book Selected Values of Chemical Thermodynamic Properties, Circular of the U.S. Bureau of Standards No. 500 (1952), in which values of heats of formation of compounds from elements in their standard states and some other properties of substances are given. 

Values of AG of formation of thousands of compounds, at 0 K and 298.16 K (25 C), are given in the U.S. Bureau of Standards Circular 500, Selected Values of Chemical Thermodynamic Properties. These values may be combined to give the values of AG for many other reactions, for which the equilibrium constants can then be calculated by use of Equation 10-24. 

Values of the standard enthalpy of formation at 25°C of some substances from the elements in their standard states are given in Tables VI-1 to VI-10. These values for the most part have been taken from the reference book Selected Values of Chemical Thermodynamic Properties, circular of the U.S. Bureau of Standards No. 500 (1952). Values are also given in Handbook of Chemistiy and Physics and other reference books. A selection of values for compounds of the transition metals, which are not included in the following tables, can be found in General Chemistty, L. Pauling, W. H. Freeman and Company, San Francisco, 3rd edition, 1970. 

Data for customary U.S. units in columns (I ), (2), and (5) taken from U.S. Bureau of Standards Circular No. 142, Table of Thermodynamic Properties of Ammonia, 1st ed., April 16, 1923. Values for columns (3) and (4) calculated from column 2. Metric conversions have been rounded. 

These figures were calculated from empirical equations given in U.S. Bureau of Standards Scientific Papers Nos. 313 and 315 and represent values obtained by extrapolation beyond the range covered in the experimental work. 

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