98 MOSSOnTS THEORY. SECT. XIV. 



able to reconcile the attraction of the molecules of mat- 

 ter inversely as the squares of the distance as proved 

 by Newton, with their mutual repulsion according to 

 the same law. But Professor Mossotti has recently 

 shown, by a very able analysis, that there are strong 

 grounds for believing that not only the molecular forces 

 which unite the particles of material bodies depend on 

 the electric fluid, but that even gravitation itself, which 

 binds world to world and sun to sun, can no longer be 

 regarded as an ultimate principle, but the residual por- 

 tion of a far more powerful force generated by that en- 

 ergetic agent which pervades creation. 



It is true that this connection between the molecular 

 forces and gravitation depends upon a hypothesis ; but 

 in the greater number of physical investigations, some 

 hypothesis is requisite in the first instance to aid the 

 imperfection of our senses. Yet, when the phenomena 

 of nature accord with the assumption, we are justified 

 in believing it to be a general law. 



As the particles of material bodies are not in actual 

 contact, Professor Mossotti supposes that each is en- 

 compassed by an atmosphere of the ethereal fluid; 

 that the atoms of the fluid repel one another ; that the 

 molecules of matter repel one another, but with less 

 intensity ; and that there is a mutual attraction be- 

 tween the particles of matter and the atoms of the fluid. 

 Forces which we know to exist, and which he assumes 

 to vary inversely as squares of: the distance. The fol- 

 lowing important results have been obtained by the pro- 

 fessor from the adjustment of these three forces : 



When the material molecules of a body are inappre- 

 ciably near to one another, they mutually repel each 

 other with a force which diminishes rapidly as the 

 infinitely small distance between the material molecules 

 augments, and at last vanishes. When the molecules 

 are still farther apart, the force becomes attractive. At 

 that particular point where the change takes place, the 

 forces of repulsion and attraction balance each other, so 

 that the molecules of a body are neither disposed to 

 approach nor recede, but remain in equilibrio. If we 

 try to press them nearer, the repulsive force resists the 

 attempt ; and if we endeavor to break the body so as to 



