Further researches have enabled me to extend this 

 formula ; ami I now offer the following as more complete 

 ncity is one of t/te effects of the interaction of atoms 

 and molecules in virtue of their pliysical properties. Just 

 as 1 1 rat is now known as a mode of motion, and is produced 

 by the friction of matter, \vc might similarly say that 



; is (i mode ofmotion.aflo^v of molecular vibrations 

 produced by the friction of molecules against molecules ( . 



rrii'us met hi en brought into different con- 



ditions), and ' r the best conductor. 



Of all the various sources of electricity which one can 

 take to prove this theory, and learn to its fullest, even if 

 only to a small extent its nature, which will answer our 

 purpose best? After carefully thinking over the various 

 sources, whether Friction machines, Voltaic cells, Dynamos, 

 Percussion, Vibration, Disruption, Cleavage, Crystallisation, 

 Solidification, Combustion, Evaporation, Atmospheric in all 

 of its varieties, Pyro, Animal, Vegetable, or Thermo- 

 electricity Thermo-electricity for many reasons appeared 

 the best 



To a considerable extent it was an untrodden field, and 

 one in which there was more promise of fresh facts 

 than in any of the others. This and other things decided 

 lection. Accordingly, during 1886 and part of 1887, 

 having time at my disposal, I was able to test what I have 

 now advanced. 



Most substances have a proportionate conductive energy 

 for heat and electricity. For heat the conduction is slow, 

 while for electricity it is all but instantaneous. The relation 

 between the two appears to be that electricity in its trans- 

 mission always generates heat, and that heat, whenever it 

 crosses two molecules in dissimilar conditions, or of 

 dissimilar specific properties, generates an electric current. 



Without passing in review the various metals which have 

 been tabulated by different writers as to their FJectromotivc 



