491 



hydrogen region, and begin to decrease beyond abont 30° K. ') 

 § 4. Table V contains values of the energy U, whicli are derived 



1) Our results point further to an increase of 8 for copper above 70° K. It is 

 true, that die increase hardly exceeds the degree of accuracy reached in our 

 measurements, but meanwhile it finds a conlirmalion in the results obtained by 

 ScHiMPFF, ZS. physik. Chem. 71 (1910), p. 257, by Richards and Jackson, ZS. 

 physik. Chem. 70 (1910), p 414, by Koref, Ann. d. Pliys. (4) 36 (1911), p. 49, 

 R. EwALD Ann. d. Phys. (4) 44 (1914), p. 1218 and by Roli.a, Gazz. chim. 

 44 1 (1914), p. 646, at temperatures between that of liquid air and room tem- 

 perature or 0° C. respectively. A curve which is drawn through our results below 

 90° K., and which represents the observations mentioned above as follows: 



gives i. a. the following values of Cp : 



Proceedings Royal Acad. Amsterdam. Vol. XVIII. 



32 



