CAPACITY FOR HEAT OF MKTAI.S AT DIFFERENT TEMPERATURES. 181 



iible to gather, ooooeraing the specific heats of the elements, which appeared to 

 us to carry sufficient weight to render the deduced values of any service in such an 

 enquiry ; many of those included should, tor the reasons given in the introduction to 

 this paper, he regarded as rough approximations only. No element has l>een omitted 

 in connection with which any satisfactory evidence concerning the specific heat at C. 

 was obtainable. 



In column I. of Table XXX., p. 180, we enumerate those elements in which the 

 agreement between the calculated and the experimental values may be regarded as 

 close (i.e., within 3 per cent.), and we have in each case indicated the percentage 

 difference and its sign. 



In column II. we place those in which the differences vary from 3 to 16 per cent., 

 including some in which the probable error may be of like dimensions ; in column III., 

 those experimental results which differ so greatly from the calculated as to exclude 

 the possibility of agreement. In the case of gases, the experimental values are 

 multiplied by 2. 



Remarks on Columns. 



Column I. The sum of the differences ( 0'5) and the distribution of the signs 

 show that the experimental values are very evenly distributed about the locus of the 

 curve. 



Column II. The experimental values of N, Na, and K do not appear to be 

 sufficiently established to lend much weight to the results. 



The experimental value of the specific heat of tin at C., as compared with that 

 of other metals examined by us, is high. It is a significant fact that tin, at 

 temperatures below C., tends to revert into the grey powder form. 



[Since the above was written, we have made determinations of the specific heat of 

 sodium at C. Two different samples were used, and the results were in close 

 agreement, giving the value 0'2863 for the specific heat. 



The few experiments at higher temperatures (50 C.) indicate that the increase in 

 specific heat with temperature is considerably greater in the case of sodium than in 

 the other metals examined by us, and is of the order of O'll per cent, per I 8 C. 



In this connection it should be remembered that sodium has the lowest melting- 

 point of all the metals considered in the above table.] 



Column III. Two curious coincidences present themselves. The calculated value 

 of C is almost exactly four times that of the diamond. 



The mean experimental value' for amorphous B is closely half of the calculated one. 



It has been shown (see, for example, Al and Pb supra) that the rate of change of 

 SS/S9 as 6 changes, varies markedly for different elements ; hence, any relation such as 

 that denoted by the equation S = 4'804 x a~'*, which holds true for any given tempe- 

 rature, cannot be valid at other temperatures. There are, therefore, serious difficulties 

 in the way of accepting any definite connection between " S " and " a " at an arbitrary 



