54 On F/iiidifj/, and 



is forced by the excess of gravity above the difference between 

 repulsion and cohesive attraction, to take a level form. 



Compression, meaning uniform pressure upon all sides of a 

 cohesive aggregate, tends to the maintenance of the relative 

 position of particles. But unequal or partial pressure has the 

 contrary effect ; and may serve like external gravity to complete 

 the counterpoise of cohesive and divellent forces, or to give 

 predominance to the one. 



A viscous liquid partakes more of the solid than of the fluid 

 state. It is a softened solid, yielding to the gravity of its own 

 particles, and liable to disruption when that power overcomes 

 their tenacity ; which consists in the excess of mutual attrac- 

 tion above repulsion. It ceases to be viscid, whenever the re- 

 pulsive energy equals the attractive. 



A non-viscid liquid partakes as much of the fluid as of the 

 solid state. In it, the intrinsic attractive and repulsive forces 

 are exactly balanced : whence the perfect mobility of its par- 

 ticles. It yields to gravity without defalcation from this power : 

 and is held together only by external means opposed to the dif- 

 fusion of the mass. It is a mean between solid and fluid con- 

 ditions ; and is that point which Latwisier contemplated as the 

 true liquid state. 



He considered likewise as a liquid form, that of a compressed 

 gaseous fluid, where gravity mediately assists to overcome 

 elasticity or excess of repulsion above attraction in the fluid- 

 This, however, is no liquid, but gas restrained by pressure. It 

 needs no increase of repulsion, but merely removal or diminu- 

 tion of -pressure, or of gravitation not its own, to manifest an 

 elasticity opposed to its gravity. To convert it into a liquid, 

 the excess of repulsive energy must be abstracted. 



According to this view, atmospheric pressure, or the gravita- 

 tion of superincumbent matter, whatever effect it has in re- 

 straining an aeriform fluid, has no concern in maintaining the 

 liquid form ; which is due entirely to a direct operation, and 

 not at all to indirect influence or mediate operation of causes, 

 whether extrinsic or intrinsic; 



Extrinsic causes are here spoken of with reference to repul- 

 sion as well as to gravity ; deeming it not quite easy to con- 



