498 



Mr. H. Tomlinson. The Influence of 



Remarks on Tables I and II. 



From the last column of Table I we learn that the thermal capacity 

 of all the metals examined increases with the temperature, a result 

 which we find confirmed by the observations of other experimenters, 

 recorded in the third column of Table II.* 



The last column of Table II shows that the results obtained by me 

 are on the whole slightly, but decidedly, greater than those of the 

 means of the other experimenters, and perhaps this may be accounted 

 for by the fact that with me the loss of heat in the transfer from the 

 hot air-chamber to the cold water is entirely compensated. 



The thermal capacities of the alloys platinum-silver and German-silver 

 are almost exactly the same as those calculated from the proportions 

 of their components ; thus the calculated thermal capacity of the 

 platinum- silver, which was composed of 2 parts by weight of silver 

 and 1 part of platinum, is 0*04877 between 0° C. and 100° C, and the 

 observed value is 0*04864. Again, the calculated thermal capacity of # 

 the German-silver, which was composed of 74 parts by weight of 

 copper, 20 parts by weight of zinc, and 6 parts of nickel, f is 0-09460, 

 and the observed value 0*09466. Such results as these are highly 

 satisfactory, as they not only serve as indications of .the trustworthi- 

 ness of the mode of observation, but also show how very closely we 

 may rely on calculating the thermal capacities of such alloys as 

 these from the thermal capacities of their component parts. 



Finally, we learn from Table II how well the observations of dif- 

 ferent observers agree with each other, so that small differences in 

 the purity of the metal J do not, as in the case of electrical conductivity, 

 make much difference in the thermal capacity. 



Relation between " Young 1 s Modulus " and Thermal Capacity per Unit 



Volume. 



It is now time to consider whether such a relationship as has been 

 mentioned in the beginning of this portion of the paper to be likely 

 to exist between thermal capacity and elasticity, does really do so, 

 and in Table III will be found the necessary data. 



From Table III we learn that, with exceptions in the cases of 

 platinum and platinum-silver, the order of the thermal capacities per 

 unit volume of the different metals is the same as the order of 



* The numbers given in this column are taken from Everett's "Units and 

 Physical Constants," p. 83, with the exception of those taken from Table I. 



f The component parts of this alloy were determined for me in the Chemical 

 Laboratory, at King's College, through the courtesy of Mr. J. M. Thomson. 



X The metals aluminium, copper, platinum, and silver were sold to me by Johnson, 

 Matthey, and Co. as chemically pure, whilst the zinc, lead, and tin were as pure as 

 could be obtained by the ordinary process of distillation. 



