126 ANNUAL OF SCIENTIFIC DISCOVERY. 



all unnecessary assumptions were avoided, and all the properties 

 of matter ex])lained upon dynamical crrounds. His hypothesis is 

 as follows : Force exists independently of matter, every position 

 in space being traversed by lines of force in every possible direc- 

 tion, each line of force being infinite in quantity. This force pro- 

 duces gravitation as follows : A single atom in space would be 

 acted upon in all directions alike, and no resultant motion would 

 ensue, but when two atoms were introduced, a mutual intercep- 

 tion of the force lines would take place, and force would become 

 associated witli the atom, and they would be impelled toward 

 each other. Atomic attractions are simply gravitations of atoms 

 towards each other, and are referable to tlie same cause. 



No such thing exists in nature as attractions and repulsions, in 

 the usual meaning, which implies that they are inherent proper- 

 ties of matter. Rejiulsions of atoms, like the separative motions 

 of celestial bodies, are due to momentum or excess of associated 

 force over gravitation. Heat, the great repulsive force of nature, 

 is simply the momentum of atoms. The tliree distinctive con- 

 ditions of matter, namely, the solid, liquid and gaseous or vapor- 

 ous conditions, he then attempted to show to depend on the relations 

 of the two op23osing forces of gravitation and momentum. When 

 the former is greater the atoms are held together in the solid condi- 

 tion. In the liquid condition they are equal, and in the gaseous 

 state excess of motion produces virtual repulsion. This hypothesis 

 explains the polar force of crystallization in a simple and beautiful 

 manner. 



The law of Mariotte, that at equal temperatures the volume of a 

 gas is in inverse proportion to the pressure, was shown to be a direct 

 consequence of this hypothesis ; — also the law that specific heat is 

 in inverse proportion to the atomic weight, and the principle of 

 equal gaseous volumes of chemical atoms, simple or compound. 

 Some other correspondences of theory with fact were pointed out, 

 and the nature of the transformation from one condition of matter, 

 by the addition or abstraction of heat or momentum, was traced in 

 detail. Ampere's theory of the identity of magnetism witli elec- 

 tricity could be well illustrated by the same models which ex- 

 hibited the motions of atoms in tliis hypothesis, and the polariza- 

 tion of light into vibrations in different planes accounted for. 

 Finally, all the phenomena of nature could be accounted for when 

 they were properly understood, b}^ referring them to the one uni- 

 versal force assumed. 



PERMEABILITY OF CAST IRON TO GASES. 



Graham discovered that iron at a red heat will absorb 4.15 

 times its volume of carbonic oxide. Observers are not agreed 

 whether the gas thus absorbed would pass inward toward the fire 

 in a stove, or outward into the atmosphere. The porosity of cast 

 iron is a well-known fact; many years ago Mr. Perkins forced 

 water through thick plates of it, and it is not, therefore, surprising 



