140 PROFESSOR W. A. TILDEN ON THE SPECIFIC HEATS OF METALS AND 



process. Tellurium and the pure metals were weighed out in the proportions 

 corresponding to the formulae Ag 2 Te, NiTe and SnTe 2 respectively, with a slight 

 excess amounting to about 1 per cent, of tellurium. The materials were then fused 

 together in a stream of hydrogen at a temperature sufficiently high to volatilise the 

 excess of tellurium. The tellurides were obtained as black, crystalline, fusible 

 substances, and were cast into cylindrical form by melting in a glass tube. 



The nickel used in the preparation of the telluride was in the form of soft wire 

 drawn from metal obtained by electrolysis. For this I am indebted to the kindness 

 of Dr. J. WILSON SWAN, F.R.S. Its specific heat was determined in the steam 

 calorimeter in order to compare it with the fused nickel made for the previous 

 experiments, but which was not found to be sufficiently ductile to admit of being 

 drawn into wire. 



SOFP Nickel Wire. 



The moan specific heat adopted as the result of the previous experiments on fused 

 nickel was *1084 for the same range of temperature.* 



Alloys of silver and aluminium have also been examined. They were prepared by 

 melting together the exact proportions of the pure metals. In the first the silver 

 largely predominates, being in the ratio required by the formula Ag 3 Al. The second 

 contains aluminium in proportion corresponding to the formula AgA.\ u , which 

 represents 75'1 per cent, of aluminium and 24 - 9 per cent, of silver. 



As in the results set forth in the previous paper, the specific heat adopted is the 

 mean of several closely concordant experiments made at each range of temperature. 

 The figures followed by E are estimated from the others which are the direct results 

 of experiment. It will be seen (Table I.) that the value for specific heat increases 

 with rise of temperature in every case except silver telluride, where the mean specific 

 heats found between 15 and 309 and 390 C. respectively are less than at lower 

 temperatures. This irregularity is attributed to the fact that during the later 

 experiments the mass cracked and it was found necessary to re-melt it several times. 

 This was done in hydrogen gas, and though no change in appearance was observed, 

 some slight change in composition or structure may have been produced. These 

 figures have, therefore, not been used in the subsequent calculations. 



* 'Phil. Trans.,' A, vol. 201, p. 38 (1903). 



