PROFESSOR KELLAND, ON MOLECULAR EQUILIBRIUM. 37 



centre; whilst the density at a given distance varies only as the attractive 

 energy of the particle. Of course, the expression density does not signify, 

 the actual amount of aggregation of particles, but merely the aggre- 

 gation so far as it depends on the particle under consideration. 



16. We may verify our conclusion with respect to the value of e, 

 by the following method : 



Conceive only one particle to exist. At a considerable distance R 

 from its centre, the principal forces which act on a particle of its 

 surrounding caloric, are the attraction of the particle and the repulsion 

 of the caloric. 



MP 



The former force is -g-,- . 



™ . . 4ntP*J r ar , 4nrP*A . „ r 1 



The latter ■— «; — .)e~ ar rdt = — ^ — \C - - e~ ar - -e~ ar \, 



R* ' J R 4 



a a 



the value of which from r = I to r = a considerable quantity is very 

 nearly 



4,*P*R MP 



hence 



Ra* ~ W ' 

 . birPB 



" " M ' 

 the same value as we obtained by the former process. 



17. We have hitherto omitted any consideration of a uniform layer 

 of caloric distributed over space, so as to act equally on every point. 

 It is clear, that the effect of such caloric will be found by retaining D 

 as the excess of density above this uniform density q. The correct 

 value of V will now be found by subtracting from its value above 

 the sum of every mass displaced by a material molecule divided by 

 its distance from the point under consideration ; hence, all we have to 

 do is to diminish V by a quantity 



- 2,q ' 3- R~ 3 * P **'B' 



