398 FRAGMENTS OF SCIENCE. 



of the subject shows at once the general harmony of 

 this conclusion with observed facts. Organic sub- 

 stances are all excellent radiators; they are also ex- 

 tremely bad conductors. The moment we pass from 

 the metals to their compounds we pass from good con- 

 ductors to bad ones, and from bad radiators to good 

 ones. Water, among liquids, is probably the worst con- 

 ductor; it is the best radiator. Silver, among solids, 

 is the best conductor; it is the worst radiator. The 

 excellent researches of MM. de la Provostaye and De- 

 sains furnish a striking illustration of what I am in- 

 clined to regard as a natural law that those atoms 

 which transfer the greatest amount of motion to the 

 ether, or, in other words, radiate most powerfully, are 

 the least competent to communicate motion to each 

 other, or, in other words, to propagate by conduction 

 readily. 



