396 SCIENTIFIC WRITINGS. 



approximately prismatic space filled with pure mercury 

 to within a ten thousandth of its value , and thus 

 solved the question of an absolute unit of resistance, 

 i. e. one resting on a definition , with an exactness 

 corresponding to the fineness of our measuring instru- 

 ments. By these means exact and comparable electric 

 measurements were first rendered possible. 



In the course of this investigation I confirmed the 

 proposition, already laid down by others, that solid 

 alloys always exhibit a greater resistance than corre- 

 sponds to the resistances of the several component 

 metals; I showed however that this does not hold good 

 for fluid metallic combinations, which retain in the 

 fluid state the resistance of the single metals unchanged. 

 This behaviour of the metals I showed could be 

 utililized for the determination of the specific resistance 

 in the fluid state of metals not readily fusible. Further 

 I discovered that the resistance of metals is considerably 

 enhanced by fusion, and that at the same time the 

 latent heat effusion increases the resistance in a higher 

 degree than the sensible heat of a solid or liquid con- 

 ductor. I found too that the increase of resistance by 

 fusion does not occur discontinuously, but that the 

 resistance rises continuously within a certain range 

 of temperature and joins without break the resistance 

 curve of the fused metal. Hence I concluded that 

 the physical processes of fusion and solidification 

 essentially consist in the absorption and liberation of 

 latent heat, which take place within a definite range 

 of temperature during liquefaction. 



