240 PROFESSOR W. A. TILDEN ON THE SPECIFIC HEATS OF METALS. 



Finally, another specimen of nickel deposited from the carbonyl compound in Dr. 

 MOND'S laboratory was submitted to experiment. The whole was melted into a solid 



button free from cavities. 



Series XTT. 



The mean specific heats of pure cobalt and nickel after fusion may now be taken 

 as follows : 



Cobalt -10303 probable error. . . '000013 



Nickel 



108301 mean of means . . '10845 

 10854 J with probable error . '000037 



Arithmetical mean . '10842 



REGNAULT found the specific heat of cobalt made from the oxalate '10G9G, and of 

 nickel '10863. 



On multiplying these numbers by the atomic weights, the products are for cobalt 

 10303 X 58'55 = 6'03, and for nickel '10842 X 58'24 = 6'31, from which it is 

 obvious that the atomic heats are not identical. 



There is no other pair of metals so nearly allied together as cobalt and nickel, but 

 with the object of testing the process further, gold has been compared with platinum 

 and copper with iron, the atomic weights and densities in each case being pretty near 

 together. 



Gold and Platinum. For the gold I am indebted to Professor Sir W. ROBERTS- 

 AUSTEN. It was practically pure, containing, if anything, a minute trace of silver. 

 It was supplied in the form of a rolled plate, and gave the following results : 



Series V. 

 Rolled Gold. S.G. 19 '269 at 20/20. 



