36 Chemistry and Physics 



No. 61. RICHARDS, T. W., and G. E. BEHR. The Electromotive Force of Iron 

 under Varying Conditions and the Effect of Occluded Hydrogen. Oc- 

 tavo, 43 pages, 6 text figures. Published 1906. Price $0.25. 



The object of this work was to determine with great precision the electro- 

 motive force of iron in contact with solutions of its salts, as a first step in the 

 exact study of the very important phenomenon of rusting. It is shown that all 

 previous investigations upon this subject were at fault because of inadequate pre- 

 cautions as to the purity of the iron and the exclusion of oxygen from the system. 

 Iron in various conditions was investigated and the effect of stresses was studied. 

 If the normal calomel electrode is taken as having a single potential difference of 

 0.56, pure compact iron has a single potential difference of 0.15. Occluded hydrogen 

 was found greatly to raise this value. The facts received brief theoretical discus- 

 sion. This work has since been repeated and verified by others. 



No. 69. RICHARDS, T. W., and A. STAEHLER, E. MUELLER, G. S. FORBES, and GRIN- 

 NELL JONES. Further Researches Concerning the Atomic Weights of 

 Potassium, Silver, Chlorine, Bromine, Nitrogen, and Sulphur. Octavo, 

 88 pages, 4 text figures. Published 1907. Price $0.50. 



This monograph includes four papers, one having been undertaken with the 

 help of each of the four assistants named above. The first consisted of a study 

 of the atomic weight of potassium essentially similar to that of sodium described 

 in publication 28, with some further precautions contributing still more to accuracy. 

 It was shown that Stas had made the same errors in the case of potassium as in 

 that of sodium and that the real atomic weight of this element is to be taken as 

 39.114, if silver is 107.93. 



The second paper describes a precise study of potassium bromide. This yielded 

 identically the same value for potassium as the chloride, leaving no doubt as to 

 the true value of the atomic weight of this element. If silver is taken as 107.88, 

 potassium becomes 39.096. 



The third paper deals with the synthesis of silver nitrate from pure silver and 

 pure nitric acid. In the course of the work a new and convenient apparatus for 

 quantitative evaporation involving quartz flasks was devised. The silver nitrate 

 was fused until constant in weight; it was carefully tested for dissolved air, re- 

 tained water, and ammonia, and nitric and nitrous acids. Only the second and 

 third of these impurities could be detected by tests proved to be adequate, and 

 these only in mere traces, less than 0.002 per cent in all. The outcome was that if 

 nitrogen is taken as 14.008, silver must be taken as 107.880. 



The fourth paper concerns the atomic weights of silver and sulphur, which 

 were evaluated by converting pure silver sulphate into silver chloride. The results 

 showed that if sulphur is taken as 32.07, silver must be 107.88. 



No. 76. RICHARDS, T. W., and W. N. STULL, F. N. BRINK, and F. BONNET, JR. The 

 Compressibilities of the Elements and their Periodic Relations. Oc- 

 tavo, 67 pages, 8 text figures. Published 1907. Price $0.50. 

 Until this investigation was undertaken almost nothing was known about the 

 compressibility of the elements. The monograph describes experiments carried out 

 by the new method detailed in Publication No. 7. Thirty-five of the solid and 

 liquid elements were investigated enough to show that the compressibilities of the 

 elements are distinctly related periodically with one another as well as with other 

 properties such as volatility and atomic volume. Among the elements investi- 

 gated, silicon was least affected by pressure, having a compressibility less than 

 one-twentieth of that of mercury, and caesium was found to be the most compres- 

 sible among the solid elements, having a compressibility about fifteen times that of 

 mercury. Liquid chlorine was found to be about half again as compressible as this; 

 and other solid and liquid elements have values ranging between these extremes. 



No. 118. RICHARDS, T. W., with the collaboration of J. H, WILSON and R. N. 

 GARROD-THOMAS. Electrochemical Investigation of Liquid Amalgams 

 of Thallium, Indium, Tin, Zinc, Cadmium, Lead, Copper, and Lithium. 

 Octavo, iv+72 pages, 12 text figures. Published 1909. Price $0.50. 

 The connected investigations described in the two papers comprised in this mono- 

 graph are a continuation of the research described in Publication No. 56. The 



