COPPER. 49 



ments, made with especial care, on the reduction of pur- 

 pureo-cobaltic chloride by hydrogen gave 59.09. (Reported 

 by Gibbs. Berlin, Bericht der Chem. Ges., 4, 1871, 789.) 



COPPER. 



Regnault, Kopp, and others have determined the specific 

 heat of copper. It corresponds to an atomic heat of about 

 6 if the atomic weight is taken at 63.3. ( Gmelin-Kraut, I. c.) 



R. Chenevix: F. H. Wollaston: 64. (O = 16); 400 

 (0=100.) 



Chenevix found 20 parts of oxygen equivalent to 100 parts 

 of copper, whence Wollaston deduces the atomic weight. 

 {Phil. Trans., IO4., 1814, 21.) 



J. J. Berzelius : 63.^96 (0 = 16) ; 395.6 (0 == 100). 



Determined by two experiments on the reduction of cupric 

 oxide with hydrogen, which gave 395.695 and 395.507. The 

 water was not weighed. [Poggend. AnnaL, 8, 1826, 182 ; and 

 Lehrbuch, 3, 1216!) 



ErdxMANN and Marchand : 63.456 (O = 16) ; 396.6 

 (0 = 100.) 



Determined by four experiments on the reduction of 

 large quantities of cupric oxide in a current of hydrogen. 

 The hydrogen was displaced by air after the completion of 

 the reduction. The weight of the oxide and of the copper 

 were reduced to vacuum, but not that of the weights em- 

 ployed. To obtain pure cupric oxide, pure vitrol was pre- 

 pared and electrolytically decomposed. The copper thus 

 obtained was dissolved in nitric acid, and the nitrate decom- 

 posed by heat. The value is the mean; the extreme differ- 

 ence is 0.056 for O = 8, or 0.112 for = 16. {Urdm.. Journ. 

 filr Prak. Chem., 31, 1844, 389.) 



Berzelius points out that these analyses vary among them- 

 selves much more than his own. He makes the difference 

 somewhat greater than it really is by neglecting the reduc- 

 tion to vacuum. [Ibid., 37, 1846, 72.) 



Ilampc shows that these analyses, correctly calculated, 

 give Cu = 63.46. {Zeitschr. fiir Berg Hiltten-und-Sal- Wesen 

 im Preus. St., £1, 1873, 261.) 

 4 



