288 HENEY A. EOWLAND 



that is by friction. In this case we can suppose the glass to take hold 

 of one end of the lines of force and the rubber the other end and it is 

 then only necessary to pull the bodies asunder to fill the space with 

 lines. The friction is merely needed to bring the two bodies into inti- 

 mate contact and remove them gently from each other. 



The following considerations may guide us in understanding the 

 details of the process. It is well known from Faraday's researches 

 that a given quantity of electricity has a fixed relation to the chemical 

 equivalents of substances. Thus it requires 10,000 absolute electro- 

 magnetic units of electricity to deposit 114 grams of silver, 68 grams of 

 copper, 34 grams of zinc, etc. 



Hence we can consider, for instance, in chloride of silver that the 

 atoms of silver are joined to the atoms of chlorine by lines of electro- 

 static force which hold them to each other. If, by rubbing the chloride 

 of silver, we could remove the chlorine on the rubber while leaving 

 the silver, we could stretch them asunder and so fill space with the lines 

 of electrostatic force. According to this theory, then, each atom has 

 a number of lines of force attached to it, and it is only by stretching 

 the atoms apart that we can fill an appreciable space with them and so 

 cause electrostatic action at a distance. 



We come to the conclusion, then, that all electrification is originally 

 produced by separating the atoms of bodies from one another, which 

 can be done by breaking contact, by friction, or by direct chemical 

 action of one substance on another, or in some other manner not so 

 common. The lines of electrostatic force in a case of electricity at 

 rest must always begin and end on matter, and they can never have 

 their ends in space free from matter. The ends can be carried along 

 with the matter, constituting electric convection, or they can slide 

 through a metallic conductor or an electrolyte or rarefied gas, making 

 what we call an electric current; but, as they cannot end in a vacuum, 

 they cannot pass through it. Thus we conclude that a vacuum is a 

 perfect non-conductor of electricity. 



The exact process by which the ends of the lines of force pass 

 through and along a conductor can at present be only dimly imagined, 

 and no existing theory can be considered as entirely satisfactory. In 

 the case of an electrolyte, however, we can form a fairly perfect picture 

 of what takes place as the decomposition goes on. Thus, in the case of 

 zinc and copper in hydrochloric acid, we can imagine the zinc plate 

 attracting the chlorine of the acid, thus stretching out the natural line 

 of electric force connecting the chlorine atom and the first hydrogen 



