CHEMISTRY AND PHYSICS. 



No. 7. RICHARDS, T. W., and W. N. STULL. New Method for Determining' Com- 

 pressibility. Octavo, 45 pages, 5 figures. Published 1903. Price $0.25. 



In this paper the defects of many previously used methods for determining 

 compressibility are explained, and new methods are suggested which are applicable 

 to nearly all liquids and solids. With the help of these methods the compressibility 

 of bromine, iodine, chloroform, bromoform, carbon tetrachloride, phosphorus, water, 

 and glass have been determined by reference to mercury in most cases as far as 500 

 or 600 atmospheres. From some of these the compressibility of liquid chlorine has 

 been inferred. Approximate determinations of the heats of compression of water 

 and mercury have been made. A new manometer for calibrating high-pressure 

 gauges is proposed. The compressibilities of the substances named above have been 

 compared with regard to their relative decrease with increasing pressure. It is 

 pointed out that usually the greater the compressibility the greater is its decrease 

 with increasing pressure. 



No. 28. RICHARDS, T. W., and R. C. WELLS. A Revision of the Atomic Weights 

 of Sodium and Chlorine. Octavo, 70 pages. Published 1905. Price $0.50. 



The investigation described in this monograph consisted of a very careful 

 quantitative study of the three ratios involving the three substances silver chlo- 

 ride, sodium chloride, and metallic silver. An effort was made to test every opera- 

 tion involved in the execution of the experiments with the greatest precision. Ex- 

 traordinary precautions were taken in purifying all the substances used. The 

 identity of materials obtained from many different sources was demonstrated in 

 order to prove the adequacy of the methods of purification. Before weighing, all 

 the substances were fused in vacuum in order to eliminate air and moisture. The 

 conditions governing the irregularities attending chemical precipitation were 

 studied more minutely than hitherto and the necessary precautions were applied. 

 It was shown conclusively that Stas's silver must have been impure and that ac- 

 cordingly his atomic weight of chlorine was in error by over 0.05 per cent, while 

 his value for sodium was nearly 0.2 per cent too high. The new values are respec- 

 tively 35.473 and 23.008, if silver is provisionally taken as 107.930, each figure 

 being diminished by 0.046 per cent if silver is taken as 107.88. 



No. 56. RICHARDS, T. W., and G. S. FORBES. Energy Changes Involved in the 

 Dilution of Zinc and Cadmium Amalgams. Octavo, 68 pages, 10 figs. 

 Published 1906. Price $0.50. 



The electrochemical and thermochemical properties of liquid amalgams were 

 investigated with a view to the further understanding of chemically generated 

 electromotive forces. Extraordinary precautions were taken against experimental 

 errors. Zinc amalgams gave potentials lower than those calculated from the gas 

 law (or law of concentration-effect) and cadmium amalgams gave potentials 

 higher than those thus calculated. As the dilution with mercury is increased, the 

 deviations diminish, and in the most dilute amalgams investigated the closest ap- 

 proach to the law ever noted in the study of solutions was found. The temperature- 

 coefficient of the potential of the cadmium amalgam cells was found to be almost 

 identical with the tension increment of a perfect gas, while that of the concen- 

 trated zinc-amalgam cell was shown to be greater. Preliminary thermochemical 

 experimentation supported these conclusions, and all the experiments were studied in 

 relation to the conclusions of Helmholtz and of Cady. A part of the work has since 

 been verified by the less comprehensive investigation of Hulett and De Lury (J. Am, 

 Chem. Soc., 30, 1812 [1908]). This investigation is continued in publication 118. 



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