368 Thoughts upon the JValure of Heat and Electricity. 



an influence exerted by one over the other. For it is difficult to 

 suppose that any natural phenomena could be caused, so entirely 

 distinct from any of the known results produced by the agency 

 of heat, where a similarity in nature and in function existed. 

 There is certainly combustion, heat, light, &c., effected by elec- 

 tricity, in common with caloric ; and this is a fair cause for sup- 

 posing at least a direct reaction between them, a mutual inter- 

 change of duties, and almost that the one is a modification of the 

 other. But no operation of mere caloric will discharge the pistol 

 containing hydrogen, or decompose water, or display opposite 

 effects at the same moment, by one portion of an instrument, or 

 original form of matter becoming negatively or positively electri- 

 fied. In developing the electricity of these substances, heat is 

 necessary, though not a high temperature, and their electricity 

 thus acquired, lasts while the body cools, though the polarities 

 become changed. It would almost seem sufficient evidence that 

 heat and the electric fluid were independent forms of matter, by 

 this assuming of polarities. The cause of their formation it 

 would require a deep insight into nature to discover. We can 

 see no analogy between this result and any of the properties of 

 caloric. An iron poker becomes magnetized by standing in a per- 

 pendicular position, and the magnetism is lost by heat. Now it 

 would be a natural suggestion, that two fluids, thus reciprocally 

 affected, were entirely opposite ; that heat, destroying the mag- 

 netic property, could not of course exist with it. Yet it has been 

 asserted that the green ray magnetized a needle exposed to it; 

 and it is not doubted that heat and light co-exist; so that caloric 

 and magnetism may be combined in the same kind of matter; and 

 as caloric and electricity are more intimately related than light 

 and magnetism, they may, for a strong reason, be found together. 

 There is some connection, as yet unknown, and I believe unsus- 

 pected, between magnetism, perhaps caloric electricity, and the 

 principle of gravitation ; for the attraction of gravitation can 

 only be considered as an effect of some undiscovered power. 

 If any division could be made of these subjects, electricity might 

 be considered as a property of the air, magnetism of the earth, 

 and caloric an universally existing principle through the 

 globe, and essential to the very being of matter. Heat may be 

 presumed the result of a reaction among the particles of bodies; 

 and one philosopher has gone so far as to suppose that a calorific 



