100 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



That they are, in many cases, pretty nearly the same appears to be a 

 fact of some significance, though this significance may be at present 

 obscure. In explanation of and apology for the very marked dis- 

 agreement of these two hypothetical temperatures in the case of 

 bismuth, and in illustration of the degree of precision needed in the 

 data used, I will say that, if (Vi -f- V $ ) for bismuth were taken as 0.98, 



/„ would be — 235°; and 

 if the ratio were taken as 

 0.99,f,wouldbel7°. Evi- 

 dently the precise deter- 

 mination of (Vi -¥• V s ) in a 

 crystalline substance like 

 bismuth is very difficult. 

 In drawing curves like 

 those of Figures A and B, 

 I sometimes ignored the 

 course of the curve for the solid just below the melting point, for 

 the reason that for some metals there was a rapid change in the 

 curvature here, as if the melting were already incipient. 



Although one can hardly study the table here given without being 

 convinced that the change of volume in fusion is very closely connected 

 with the change of resistance, and is in some large measure the cause 

 of it, examination of the known phenomena of conduction in the solid 

 state shows that we cannot account for changes of resistance by con- 

 sideration of changes of volume only. For example, the following 

 Table Y, the second, third and fourth columns of which are taken 

 from an article by E. Griineisen, 26 shows by comparison of the fourth 

 and fifth columns that increase of volume is not a very important fac- 

 tor in the increase of resistance which accompanies rise of tempera- 

 ture at constant pressure in the metals here exhibited. 



26 Bericht. d. Deutschen Physikalischen Gesellschaft, Heft 6, S. 198 (1913). 



