84 ON THE STRUCTURE OF ATOMS. 



to separate from each other. It is as if the atoms were made up 

 of two kinds of sub-atoms, one kind attracting and the other re- 

 pelling all others. If the one kind attracted according to the 

 inverse square of the distance, as is the case in the attraction of 

 gravitation, and if the other kind repelled simply as the distance, 

 which is the law of the gases and probably of all repellent forces, 

 then of course in the separation of molecules composed of these 

 two kinds, there would always be a point where the repellent 

 force decreasing simply as the distance would overbalance the 

 attracting force decreasing as the square of the distance. 



In organic compounds there are numerous series which increase 

 regularly in the complexity of molecules, by the successive addi- 

 tions of CH 2 such as the alcohol, the ether, and the ethyl series. 

 Now it is found that with a considerable degree of regularity 

 the addition of each carbon atom raises the boiling point of the 

 compound from fifty to sixty degrees, Fahr., while each hydrogen 

 atom lowers it about ten degrees, the average of the CH 2 group 

 being about thirty-five degrees rise. Although variable and de- 

 pending somewhat on the other elements in the compound, yet this 

 change in the boiling point is so constantly in one direction and 

 so nearly uniform as to indicate conclusively that there is a law 

 connecting the two occurrences. The evident meaning of this 

 fact is that carbon adds to the cohesive force of molecules, while 

 hydrogen takes away from it. The balance of the force in the 

 carbon atom is an attraction, while in the hydrogen it is a repul- 

 sion. This is in accordance with the nature or properties of each. 

 Carbon has never been volatilized or even fused by any heat 

 that it is in the power of man to control. There is seemingly no 

 principle of repulsion in it. On the other hand, hydrogen shows 

 no signs of atomic cohesion ; there is no force which can press it 

 or freeze it into close enough contact to make it take the form of 

 a liquid or solid. The principle of atomic attraction seems to be 

 wholly absent from its units. Hydrogen is the most electro pos- 

 itive of all the elements, and as is well known the positive or 

 vitreous electricity is that which makes all light bodies repel 

 each other. While carbon stands at the head of the electro 

 negative solid elements, which form of electricity makes light 



