302 TRANS. OF THE ACAD. OF SCIENCE. 



and the latter has discovered numerical relations between 

 these two forces. 



"By chemical affinity we can directly produce electricity. 

 There are few if any chemical actions which cannot be ex- 

 perimentally made to produce electricity. 



"Voltaic action is chemical action taking place at a dis- 

 tance, and the Daltonian equivalent numbers are the expo- 

 nents of the amount of voltaic action for corresponding 

 chemical substances. 



"Faraday established first the laws of equivalency be- 

 tween chemistry and electricity, and Oersted those between 

 electricity and magnetism. 



"Light and heat are but modifications of the same force. 



" Heat is a mechanically repulsive force in matter, tending 

 to move the particles of all bodies to separate them from 

 each other. Heat is molecular motion. 



" Of absolute rest nature gives us no evidence ; all matter is 

 ever in movement, not merely in masses, as with the plane- 

 tary spheres, but also molecularly, or throughout its most 

 intimate structure ; thus, every alteration of temperature 

 produces a molecular change throughout the whole sub- 

 stance, heated or cooled ; slow chemical or electrical actions, 

 actions of light, or invisible radiant forces, are always at play ; 

 so that as a fact we cannot predicate of any portion of mat- 

 ter that it is absolutely at rest. 



" Light, for a long time recognised only in its visual effects, 

 produces constantly changes in the earth and atmospere no 

 less than in organized structures. Thus, every portion of 

 lio-ht may be supposed to write its own history, by a change 

 more or less permanent in ponderable matter." 



" Are not gross bodies and light convertible into each 

 other, and may not bodies receive much of their activity 

 from the particles of light that enter into their composition ? 

 The changing of bodies into light and light into bodies is 

 very conformable to the course of nature, which seems de- 

 lighted with transmutations." — Newton. 



" All the transformations of matter around us, the power 

 exhibited in the growth of plants, in the functions and mo- 

 tions of animals as well as in the winds, are all referable to 

 impulses received from the sun." — Henry. 



" The power which is evolved in the combustion of coal 

 is merely the equivalent of the force, which was expended in 

 decomposing the carbonic acid which furnished the carbon 

 to the primeval forests of the globe ; and the power, thus 

 stored away millions of years before the existence of man, 

 is now employed for the comfort of our race." — Henry. 



" We know, experimentally, that from electricity we can get 

 heat, and from heat, as in the case of the thermo-electric pile, 

 we can get electricity. 



