450 FRAGMENTS OF SCIENCE. 



conductors. The moment we pass from the metals 

 to their compounds we pass from good conductors to 

 bad ones, and from bad radiators to good ones. Water, 

 among liquids, is probably the worst conductor; 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 Desains fur- 

 nish a striking illustration of what I am inclined to 

 regard as a natural law that those atoms which 

 transfer the greatest amount of motion to the aBther, 

 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. 



