Prof. Norton on Molecular Physics. 197 



gravitation, which cannot be found, primarily, in any supposed 

 motion of gross atoms in an isolated condition. It should be 

 observed, too, that the dynamical condition of atmospheres here 

 considered is really a necessary consequence of the first opera- 

 tion of the force of attraction of atoms upon the surrounding 

 aether, if the elasticity of the aether be perfect. 



A different view of the possible nature and origin of the mole- 

 cular forces from that which has been given, may be obtained 

 by changing our stand-point. 



We may conceive the same three forces, viz. one of attrac- 

 tion, and two of repulsion, to be in operation, but we may re- 

 place the forces of electric attraction and repulsion by equivalent 

 forces propagated through the universal aether. This may be 

 realized as a physical conception by regarding the atoms of the 

 molecules and those of the surrounding electric aether, each en- 

 compassed by its aethereal atmosphere, as being, or rather their 

 atmospheres, in the dynamical condition of alternate contraction 

 and expansion, and thus as being centres from which proceed 

 oscillatory waves, and that, as the result, in accordance with the 

 general theory so ably advocated by Professor Challis, the elec- 

 tric atoms of two atmospheres may repel each other, and the 

 central atoms which they surround may also repel each other ; 

 the general result being that similar atoms repel, and dissimilar 

 attract. Upon this view the forces we have deduced from the 

 dynamical state of the electric atmospheres, which must still be 

 in operation, must be overshadowed by those now considered. 

 Upon the former idea it is the forces now derived from the dyna- 

 mical state of the aethereal atmospheres that must be oversha- 

 dowed by the others. A discussion of phenomena can alone de- 

 cide which of these two general views should be adopted. In 

 the present memoir we shall chiefly occupy the ground first taken. 

 Among the physicists of the present day there seems to be a 

 growing inclination to discard the notion of an electric fluid as 

 distinct from the aether of space, and attempts have been made 

 by Challis, Tyndall, and others, to frame a consistent dynamical 

 theory of molecular forces and phenomena based upon the sup- 

 posed existence of only two forms of matter, viz. gross matter, 

 and the aether of space. The fundamental position taken by 

 these distinguished physicists is that the molecular forces, inclu- 

 ding heat, are conveyed by purely oscillatory waves, and origi- 

 nate in a vibratory motion of the ultimate particles of bodies. 

 Against this idea, however plausible it may seem, and however 

 admirable may be the ingenuity and skill with which it has been 

 sustained, many serious objections may be urged. One or two 

 of these may be briefly stated. 



1. No possible mode of explaining the phenomena of electri- 



