226 On the Relation of Specific Heat to Atomic Weight. [Mar. 9, 



"The Specific Heats of Metals and the Eelation of Specific 

 Heat to Atomic Weight,— Part III." By W. A. Tilden, 

 D.Sc, F.E.S., Professor of Chemistry in the Eoyal College of 

 Science, London. Eeceived March 9, — Eead March 17, 1904. 



(Abstract.) 



The object of the experiments, of which an account is given in this 

 paper, was to determine whether the atomic heats of the elements 

 entering into combination are preserved in the compound at all 

 temperatures, previous results obtained by the author and others 

 having shown that the specific heats of metals of small atomic weight, 

 such as aluminium, increase very rapidly with rise of temperature. 



As it is not possible to determine the specific heat of sulphur 

 throughout a long range of temperature, tellurium was chosen for 

 experiment. Compounds of tin, silver and nickel with tellurium were 

 prepared, and two alloys of silver and aluminium. The average 

 specific heats of all these elements, except tin, were determined over 

 various intervals from the boiling point of liquid oxygen to nearly 

 500° C. in the case of the less fusible elements, a range of about 

 680° C. From these mean specific heats the true specific heats at 

 intervals of 100 Centigrade degrees absolute temperature were calcu- 

 lated, and from the specific heats the atomic heats were deduced. The 

 mean specific heats of the compounds, formed by their union, were 

 also determined, and from these data the moelcular heats of the 

 compounds calculated. On comparing the sum of the atomic heats of 

 the elements present with the molecular heat of the compound at the 

 successive temperatures, it was found that there is throughout a close 

 concordance. The order of difference may be shown by one example — 



Nickel Telluride, NiTe. 



Temperature, Sum of atomic heat Molecular heat of 



absolute. of Ni and Te. NiTe. 



100° 9-20 8-38 



200° 11-08 11-35 



300°.... 12-22 12-41 



400° 13-00 12-92 



500° 13-49 13-15 



600' 13-85 13-28 



700° 14-11 13-35 



The results of these experiments show that Neumann's law is 

 approximately true, not only at temperatures from 0° to 100° C, but at 

 all temperatures. They thus support the view that the specific heat of 



