Mr. J. Gill on the Dynamical Theory of Heat. 367 



the occurrence of which will hardly be attributed to the di- 

 equivalentic nature of oxygen. 



Again, certain chlorides, which are usually supposed to be 

 fully saturated, unite with water, a substance in which the di- 

 equivalentic oxygen is understood to be completely satisfied. 

 Thus we have the hydrates 



LiCl +7iAq (ti=1 or 2?), 

 NaCl + 2Aq, 



but not a hydrated chloride of potassium. The formation of 

 many double salts, and of direct combinations with water, appear 

 to me to be only explicable on the ground here proposed. 



This question is not verbal. Affinities are, tacitly at least, 

 taken into account in all our reasonings ; it is impossible for the 

 theory of saturation to be independent of them. The defect in 

 the theory consists in this — omitting to notice the fact that in- 

 terchangeable weights of the same equivalence order do not 

 usually represent precisely similar affinities. Hence we may 

 arrive at the following general statement : — Any two radicals are 

 not equal in saturating power for a third, unless they are equal 

 in equivalency and affinity also ; and in most cases of combina- 

 tion there is still residual saturability, due to affinity, enabling 

 the new compound itself to enter into combination. 



XLV. On the Dynamical Theory of Heat. 

 By Joseph Gill, Esq.* 



NOTHING in the universe can be supposed to be in a state 

 of isolation j a lone body is evidently a physical impossi- 

 bility ; and therefore it seems impossible to trace back to an 

 ultimate source any physical phenomenon displaying the action 

 of energy or force ; for we can perceive no material origin of 

 power, but only a circulation of existing force distributed though - 

 out all the matter of creation. Wherever an increase of energy 

 appears in any portion of matter, we may assume that an equi- 

 valent of energy must have disappeared from some other por- 

 tion of matter, as the phenomena are only indications of dis- 

 turbed equilibrium. When a weight is raised above the surface 

 of the earth, it acquires potential energy in the shape of an in- 

 creased amount of the attraction of gravitation, which must have 

 cost an expenditure of an equal amount of energy from some 

 other body. When a spring is wound up, or an elastic fluid 

 compressed, potential energy appears in the shape of repulsion 



* Communicated by the Author. 



