THE UNDERLYING FACTS OF SCIENCE 567 



Positive and Negative Ions 



An ion is a charged atom, an atom carrying a quantity of electricity, 

 such, for instance, the dissociated atoms of an electrolyte. Ions can be 

 compared to diminutive Leyden jars, and as it has been discovered that 

 they all carry the same charge and that each atom has the same electri- 

 cal capacity, the physicist has been enabled to count the actual number 

 of ions in any gas by the electrical properties of the gas. If an ion is 

 electro-positive, it is known as a cation ; if electro-negative, as an anion 

 — two old words due to Faraday, which are immediately related to the 

 familiar terms of cathode and anode. 



Whatever the essential difference between them may be, the two 

 electrical states (-f- and — ) may be said to differ chirally only, or, to 

 give a more distinct if rather crude mechanical analogy, one may 

 imagine that two discs, each suspended by a thread in its center, are 

 revolving at a high uniform speed ; if the} 7 revolve in the same direction 

 they will spring apart as soon as they come into contact, part of their 

 motion of rotation being converted into motion of translation; if they 

 revolve in opposite directions their motions will not interfere, in other 

 words they will be " in mesh." Thus, according to this conception, each 

 is the enantiomorph, or opposite form, of the other ; positive and nega- 

 tive charges of ions are equal but opposite. This idea of opposite 

 charges owing their difference to opposite directions of rotation is only 

 a working hypothesis, but is worth keeping in mind. 



Distinction between Energy and Eorce 



Having adopted negative and positive ions as the basis of matter, 

 we must now examine the distinction between force and energy before 

 going any further into the sub-atomic world. Force is the action, the 

 manifestation of energy, just as visibility is a physiological manifesta- 

 tion of light. Light, in the abstract, is energy ; in the concrete, as some- 

 thing that we see, it is a force. It is propagated as energy and mani- 

 fested as a force ; force, therefore, always implies matter. 



As we shall have opportunities to see later, all energies are almost 

 certainly modes of motion. Matter, on the other hand, is perhaps best 

 described as whatever can occupy space, but this description is not suited 

 to all theories. If motion is an essential property of matter, matter 

 might be best described as whatever possesses energy in virtue of its 

 motion ; but in this essay the nature of matter will be discussed, and not 

 its structure. 



The ether, in which energy is manifested, may be said to have owed 

 its recognition to the impossibility of believing in action at a distance 

 and through a void space. Sir William Crookes at one time suggested 

 a fourth state of matter for the ether; before accepting this theory, 

 however appropriate it may appear, it seems reasonable that all the 



