A KINETIC THEORY OF MATTER. 249 



buffers, or, which amounts to the same thing, 

 attributing to them repulsive forces sufficiently 

 powerful at very short distances to absolutely 

 prevent impacts between solid and solid ; unless 

 we adopt the equally repugnant idea of in- 

 finitely small perforated solids, with infinitely 

 great fluid circulations through them. Were it 

 not for this fundamental difficulty, the hydrokinetic 

 model gas would be exceedingly interesting ; 

 and, though we could scarcely adopt it as 

 conceivably a true representation of what gases 

 really are, it might still have some importance 

 as a model configuration of solid and liquid 

 matter, by which without elasticity the elasticity 

 of a true gas might be represented. 



But lastly, since the hydrokinetic model gas 

 with perforated solids and fluid circulations 

 through them fails because of the impacts 

 between the solids, let us annul the solids and 

 leave the liquid performing irrotational circulation 

 round vacancy, 1 in the place of the solid cores 



1 Investigations respecting coreless vortices will be found in a paper 

 by the author, " Vibrations of a Columnar Vortex," Proc. R. S. ., 



