HISTORICAL INTRODUCTION. 7 



dilute amalgam, and its reversible assimilation by the concentrated. This 

 consideration raises the calculated electromotive force somewhat, but Haber 

 pointed out the fact that the correction is less than the probable experimental 

 error of Meyer's results. The possible effect of this compound in causing 

 abnormal osmotic pressures was not considered, and no new experimental 

 evidence was offered. In closing he entered a plea for more accurate experi- 

 mental work on concentration cells to verify his theoretical deductions. 



The nature and electrical behavior of cadmium amalgams was the subject 

 of a long and interesting paper by H. C. Bijl, 21 published in the same year. 

 Herein he recounts his measurements of the cells 



Hg, Hg 2 S0 4 , CdS0 4 solution, HgCd^ 

 and 



Hg, Hg,S0 4 , CdS0 4 solution, Cd. 



He constructed curves showing the effect of concentration and tempera- 

 ture upon normal cadmium elements ; his potentials appeared to be definite 

 within a tenth of a millivolt very accurate work, considering the experi- 

 mental difficulties presented by solid amalgams. He showed that in a hetero- 

 geneous equilibrium of liquid and solid cadmium amalgams both phases had 

 the same electromotive force. Finally, he calculated various heats of amal- 

 gamation and heats of crystallization by the method of Richards and Lewis. 

 Owing to the complexity of the phenomena observed, his treatment of 

 results is necessarily empirical, and contributes little to the theoretical knowl- 

 edge of concentration effects per se. 



In 1903 Roozeboom and Van Heteren, 22 using the method of Richards and 

 Lewis, fixed the heat of amalgamation of tin at 3,000 calories. 



The subject received a comprehensive theoretical treatment from the stand- 

 point of the Phase Rule in the same year by W. Reinders. 28 



The most recent work upon the subject is that of J. F. Spencer, 84 pub- 

 lished after most of the present work was completed. This work is mainly 

 interesting on account of the clever device used in preparing the amalgams ; 

 but Spencer did not strive to attain great accuracy. 



Zeit. Phys. Chem., 41, 641 (1902). 

 'Chem. Cent. Blatt, 74, II, 866 (1903). 

 Zeit. Phys. Chem., 42, 225 (1903). 

 Zeitschr. Elektrochem., 11, 681 (1905). 



