Nature and their Mutual Dependence. 3 



different hinds of energy, as energy of heat, mechanical energy, the 

 energy produced by the mutual effect of chemical forces, fyc, cannot 

 be of different essence, but that all the various kinds must be looked 

 upon as one and the same energy, as, for example, mechanical 

 energy. 



As heat consists in the motion of the particles of bodies, it 

 follows from this i 



1 i That the material particles of which bodies consist are in con- 

 tinual motion, even when the particles of the body seem to be at 

 perfect rest ; and 



2. That, in investigations into the internal motions to which 

 the bodies are subject, we need not look upon heat as a particular 

 force, but rather as the result of the existing attractions and repul- 

 sions in connexion with certain quantities of motion imparted to 

 the particles of the body. 



As to the condition in which the material particles of a body 

 are, it is most natural to admit, with Davy, that, according to 

 their nature, the smallest elementary particles of the body pos- 

 sess a certain electric force, through which they attract or repel 

 the other material particles of the body. The proportions between 

 the quantities of the various elements contained in the body, as 

 well as the number of the different elements and the quantity of 

 their electric forces, determine the positions of equilibrium of the 

 individual particles as depending upon the adjacent particles 

 and their internal groupings in bodies. About these positions of 

 equilibrium, which for each individual particle are determined by 

 the attractions and repulsions of all the other particles, the par- 

 ticles attracted and repelled continually vibrate on account of the 

 imparted momentum ; and, in my opinion, the heat of the body 

 consists in this motion, which, like any other kind of motion, 

 may be more or less, according to circumstances. Thus it is 

 obvious that the internal quantity of energy in a body will in- 

 crease as well when a new quantity of energy, whether in the 

 shape of mechanical energy, or of heat, electricity, &c, is im- 

 parted from one body to another, as when those forces are 

 increased by which the particles of the body are moved among 

 themselves. On the contrary, the quantity of energy will de- 

 crease when some part of the motion contained in the body is 

 conducted into other bodies, or when the forces decrease by which 

 the particles of the body are moved. 



When no energy is imparted to or taken away from the body, 

 and the forces by which the particles of the body are moved among 

 themselves do not change, then the energy contained in the body will 

 remain always the same. 



Now the problem is to determine the proper mathematical ex- 

 pressions for the energy contained in a body. In consequence of 



B2 



