104 THEORY OF MOLECULAR VORTICES. SECT. XIV. 



directly as their mass and inversely as the square of the distance, 

 which is precisely the law of universal gravitation. 



Thus, on the hypothesis that the mutual repulsion between the 

 electric atoms is a little more powerful than the mutual repulsion 

 between the particles of matter, the ether and the matter attract 

 each other with unequal intensities, which leaves an excess of 

 attractive force constituting gravitation. As the gravitating force 

 is in operation wherever there is matter, the ethereal electric 

 medium must encompass all the bodies in the universe ; and, as 

 it is utterly incomprehensible that the celestial bodies should 

 exert a reciprocal attraction through a void, the Professor con- 

 cludes that the ethereal electrical medium fills all space. 



It is true that this connexion between the molecular forces and 

 gravitation depends upon hypothesis ; but in the greater number 

 of physical investigations some hypothesis is requisite in the 

 first instance to aid the imperfection of our senses ; and when the 

 phenomena of nature accord with the assumption, we are justified 

 in believing it to be a general law. 



Mr. Rankin's theory of molecular vortices, or the molecular 

 structure of matter, is independent of electricity. According to 

 his hypothesis, each atom of matter consists of an inappreciably 

 small nucleus, encompassed by an elastic ethereal atmosphere 

 which is retained in its position by attractive forces directed 

 towards the molecule, whilst the molecules attract each other in 

 the direction of straight lines joining their centres. The nuclei 

 may either be solid, or a high condensation of the atmospheres 

 which surround each with decreasing density. When the attrac- 

 tion between the molecules is such that the elasticity of the atmo- 

 spheres is insensible, the body is a perfect solid, the rigidity of 

 which bears a certain definite proportion to the elasticity of the 

 volume. When the atmospheres are less condensed and the 

 attraction of the molecules merely produces a cohesive force 

 sufficient to balance the atomic elasticity of the atmosphere, the 

 body is a perfect liquid ; and when the attraction of the molecules 

 is very small compared with the elasticity of their ethereal at- 

 mospheres, the body is a perfect gas. These atmospheres are 

 supposed to be portions of the ethereal medium which penetrates 

 into the interstices of every substance, and their elasticity to be 

 due to the heat generated by the centrifugal force or oscillations 

 among their atoms, for motion is the cause of heat, the force 



