1896.] 



on Electric BesearcJi at Low Temperatures. 



253 



magnetic field, conductors dissipate this energy at very different 

 rates. Some, like silver and copper, whicli have the lowest rates, 

 are elements of low valency and relatively small molecular volume, 

 and have probably a simple molecular structure ; others, like alloys 

 of high resistivity, have in all probability a more complex molecular 

 structure. Both this last, as well as the molecular mobility charac- 



Fig, 9. 

 Resistivity curve of mercury in terms of platinum temperature. 



teristic of the liquid state, are conditions which bestow the power of 

 taking up rapidly and dissipating the energy of the electro-magnetic 

 field, and this energy has to be kept supplied from external energy- 

 transforming sources. We cannot, however, at present profitably 

 construct further mechanical hypotheses to account for this difference 

 between conductors, in the presence of our great ignorance about 

 ether, molecules and energy. 



In passing from the liquid to the solid state there is generally an 

 immense increase in the conducting power of metals. This is well 



