CAPACITY FOR HEAT OF MI.TAI.S AT DIFFERENT TEMPERATURES. 183 



exceedingly small error in their coefficients over the range C. to 100' C. would 

 account for considerable discrepancies in the values of their Atomic Heats at absolute 

 zero, the more especially as the resulting values of S are multiplied by factors ranging 



IV. mi 63 to 200. 



Experimental errors, however, could not account for such divergent results as those 

 given by Al and Fe, hence either the atomic-heat curves of these two metals undergo 

 change at low temperatures, or their values at absolute zero must be lower than that 

 of the others in the above list. 



If we assume the continuity of the paths of the six metals above referred to and 

 deduce their respective specific heats at -273C. from the mean atomic heat (4'813),and 

 for the other two points on the parabola employ the values at C. and 100 C., we 

 obtain the following equations (t being expressed in the absolute scale)* : 



Cu . . . . S = 0'0758 (1+0-0008352-0'00000039J J ), 



Zn . . . . S = 0-07374 (l+0-0011155-0-000000807t 3 ), 



Ag . . . . S = G'0447 (l+0-00122A-0-00000122< a ), 



Cd . . . . S = 0-0429 (l+O-OOlSSSGf-O'OOOOOHSG^), 



Sn . . . . 8 = 0-0405 (1 + 0'0014514<-0-0000009665**), 



Pb ..... S = 0-02327 (1 + 0-001544<-0-00000166*). 



If the values of S at the various temperatures at which it was determined by us are 

 now tleduced from these equations, it will be found that the differences between the 

 experimental and the calculated values are very small, in, no instance exceeding 0'3 per 

 cent., and in most cases much less. 



The remarkable approximation between the hypothetical value of the atomic heat 

 at C. (4'804) of a body with atomic weight 1, and the likewise hypothetical value 

 of the atomic heat of this group of metals at alolute zero (4'813), is probably a 

 coincidence, but may possibly be of some significance. 



APPENDIX II. 



An inspection of the atomic heats of the metals investigated by us indicates that 

 those of low melting-points have high atomic heats. This is true throughout the 

 range C. to 100 C., if the values at any given temperature within that range are 



* Many equations of MI exponential nature, and also of the forms suggested by Professor PKRRY 

 (Phil. Trans.,' vol. 194, pp. 250-255) have been investigated, but none of them fitted the experimental 

 results so closely as the parabola. 



