PROFESSOR KELLAND, ON MOLECULAR EQUILIBRIUM. 29 



on the thickness of the solid, provided the solid be very thin, but it 

 can scarcely be conceived to do so in other cases, much less to vary 

 equally with the superficial extent of the surface itself. 



4. In order then to determine as nearly as possible, what is the 

 law of distribution of the particles of caloric, or the universally diffused 

 system of particles, as well as what is the law of aggregation of the 

 material particles, which determines whether the arrangement have the 

 properties of elasticity, fluidity, solidity, crystalline arrangements, &c. 

 I have examined a number of different arrangements, and investigated 

 the conditions of their equilibrium and stability. 



In the present part, I have said little about the application to dif- 

 ferent states of consistence, deeming it more prudent to make a series 

 of calculations in the first place. In fact, it is most probable that the 

 forms of the results will in all cases, as they certainly are in those 

 I have already tried, be very different from those which a popular view 

 of the subject would suggest. In my treatise on Heat, however, will 

 be found some applications roughly stated, which I hope more fully to 

 investigate in the sequel. 



Investigation of the Conditions of Equilibrium. 



5. I purpose to commence my investigation, by retaining M. Mos- 

 sotti's hypothesis of two systems of particles repulsive towards atoms 

 of their own kind, but each respectively attractive towards the atoms 

 of the other. We will call one system of particles caloric, and the 

 other matter; the masses of the atoms of the former being very small 

 compared with those of the latter. We will suppose the former dis- 

 tributed through space, whilst the latter occupy only certain given 

 positions: in both, the density at different points will be essentially dif- 

 ferent, but the particles of the latter medium, will in all cases be sup- 

 posed wherever they exist, to be much more widely separated than those 

 of the former, so that a material particle may be considered as a nucleus, 

 about which the particles of caloric are collected, so as to form its 

 atmosphere. 



