January, 1941
INDUSTRIAL AND E N G INEERING CHEMISTRY
other than mechanical treatment. The difference in the copper content may partially account for the results shbavn. Walker (IO), Burgess and Aston (8), and Marzahn and Pusch (7) all reported a marked decrease in the sulfuric acid oorrosion rate of copper-bearing steels. However, the copper content of the steels studied in this investigation was much lower than in previously reported investigations. The effect of traces of copper on the atmospheric corrosion of steels is well established, but it is not yet clear as to whether small traces of copper have a similar effect in acid corrosion.
Acknowledgment The author is indebted to R. F. Besner for part of the data on hot-rolled specimens, and to E. Nagle for chemical analyses.
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Literature Cited (1) Bryan, J. M., Trans. Faraday SOC., 31, 1714 (1935). (2) Burgess, C. F., and Aston, J., J. IND. ENC.CHEM.,5, 458 (1913). (3) Chappell, C.,J . I r o n Steel Inst., 85, 270 (1912). (4) Daeves, K.,and Eisenstecken. F., Stahl u. Eisen, 56, 417 (1936). (5) Evans, U. R., “Metallic Corrosion, Passivity and Protection”, p. 18,London, Edward Arnold & Co., 1937. (6) Hadfield, R., and Friend, J. N., J . I r o n Stet2 Inst., 93,48 (1916). (7) Maraahn, W.,and Pusch, A., Korrosion ZL. Metallschzctz, 7, No. 2, 34 (1931). (8) Ram,‘%, i.Soc, Chenz. Ind., 54, 107T (1935). (9) Speller, F. N., “Corrosion, Causes and Prevention”, 2nd ed., p. 504, New York, MoGraw-Hill Book Co., 1935. (10) Walker, W. H., Proc. Am. SOC.Testing Materials, 11, 615 (1911). PREBENTBD before the Divieion of Industrial and Engineering Chemistry a t the 100th Meeting of the American Chemical Society, Detroit, Mioh.
Activitv Coefficients of Gases J
Calculation from the Beattie-Bridgeman Equation of State SAMUEL H. MARON AND DAVID TURNBULL Case School of Applied Science, Cleveland, Ohio
The Beattie-Bridgeman equation explicit in volume is employed to derive an equation for the activity coefficients of gases as functions of pressure and temperature. The equation is applied to the calculation of the activity coefficients of nitrogen, hydrogen, and ammonia. The calculated results are compared with the activity coefficients for these gases obtained graphically. The agreement is shown to be satisfactory over a wide range of pressure and temperature. It is further shown how the derived equation may be utilized to obtain I(, values for gaseous equilibria as analytic functions of pressure and temperature. Applied, for example, to the ammonia equilibrium, the equation for I
