130 ELEMENTS OF STATIC ELECTRICITY. 



the only sources from which an electric machine can 

 derive electricity. 



With the common friction machine a connection 

 with the earth is indispensable, and only a very limited 

 charge can be obtained without it ; the transfer being 

 either from the earth to the machine, or from the ma- 

 chine to the earth, as explained on page 99. Hence it 

 is often compared to a pump, drawing electricity from 

 the earth through a chain. Remove the chain and the 

 supply ceases. 



But with the Topler a similar earth connection 

 diminishes the charge ; showing a loss instead of an 

 increase of charge. Indeed, perfect insulation of the 

 generating parts is an essential feature of the machine. 



To demonstrate this more perfectly, let the machine 

 be put in operation on an insulated platform, when it 

 will be found that there is not the slightest perceptible 

 diminution of electric energy. It is evident, then, that 

 the earth is not its source of supply. 



A certain amount is, no doubt, obtained from the 

 material of the machine itself; but this source would 

 soon be exhausted by such experiments as the charg- 

 ing of a large Leyden battery ; whereas such a battery 

 may be charged without diminishing the energy of the 

 machine. 



The air, then, is the only remaining source, and the 

 large amount of ozone generated by this machine is 

 conclusive evidence of its electro-chemical action on 

 the air, and strong, presumptive evidence that the air, 

 thus acted upon, has furnished the electricity whose 

 action has changed the oxygen to ozone. 



This would imply that ozone is the result of depriv- 

 ing air of a portion of its electricity ; whereas if the 



