450 MOSSOTTI ON THE FORCES WHICH REGULATE 



sion of the two fluids constitutes only a single force, equal to each of the 

 two attractive forces. If then, witli the equilibrium of the fluids, it is 

 desired to find the equilibrium of the masses also, an equal repulsion 

 must be allowed between the molecules ; since the bodies would other- 

 wise forcibly attract each other. But such an attraction is contrary to 

 what we learn from experience. He felt at first a strong objection to 

 the admission of such a repulsive force between the material molecules, 

 as being opposed to the idea entertained of their mutual attraction, 

 which was so clearly demonstrated on Newton's principles. But a 

 little reflection satisfied him that this admission contained nothing that 

 was opposed to facts, or, as he might rather have said, that was not con- 

 firmed by facts. Universal attraction itself may follow as a conse- 

 quence from the principles which regulate the electric forces : for if 

 we suppose that, the masses being equal, the repulsion of the molecules 

 of matter is a little less than their attraction of the atoms of the jether, 

 or than the mutual repulsion of tlie atoms themselves, this will be sufti- 

 cient to leave an excess of attraction which, being directly as the pro- 

 duct of the masses and inversely as the square of the distance, would 

 exactly represent the universal attraction. 



2. While reflecting on these principles, in a course of lectures on 

 natural philosophy which I gave at the University of Buenos Ayres, I 

 conceived the idea, that if the molecules of matter, surrounded by their 

 atmospheres, attract each other when at a greater, and repel each other 

 when at a less distance, there must be between those two distances an 

 intermediate point at wliich a molecule would be neither attracted nor 

 repelled, but would remain in steady equilibrium ; and that it was very 

 possible this might be the distance at which it would be placed in the 

 the composition of bodies. I thought the idea of sufficient importance 

 to fix it in my memory, but did not at the time pursue its development 

 further. 



On my return to Europe I learned, through the reading of some 

 memoirs, and in the course of conversation with men of science, that 

 the attention of geometers was particularly directed to the molecular 

 forces, as being those which may lead us more directly to the know- 

 ledge of the intrinsic properties of bodies. I was thus led to recall my 

 ideas on the subject, and set about subjecting them to analysis. The 

 results of my first investigations I here submit to the judgement of 

 philosophers. 



I have supposed that a number of material molecules are plunged 

 into a boundless eether, and that these molecules and the atoms of the 

 aether are subject to the actions of the forces required by the theory of 

 jEpinus, and then endeavoured to ascertain the conditions of equili- 

 librium of the aether and the molecules. Considering the aether as a 

 continuous mass, and the molecules as isolated bodies, I found that, if 



