156 Rutherford: Modern 



tricity, namely, negative electricity, which is carried in 

 small definite units by the electrons. These electrons 

 are a mobile constituent of all matter and are able to 

 move freely through metals. 



A negatively electrified body is one which has more 

 than its normal complement of electrons, while a pos- 

 itively charged body is one that has lost one or more of its 

 component electrons. This point of view is remarkably 

 analogous to that employed by Franklin in his one fluid 

 theory, with the difference that negative electricity plays 

 to-day the part that he assigned to positive. The elec- 

 trical fluid of Franklin is atomic in structure, and is 

 made up of electrons which consist of actual disembodied 

 electrical charges. With these alterations, the methods 

 of expression used by Franklin in discussing positive and 

 negative electricity is very similar to that in use to-day. 



It is certainly a remarkable and noteworthy fact that 

 the theory of Franklin put forward at a time when the 

 knowledge of electricity was of the scantiest character, 

 should have survived, even in a modified form, during 

 a century which has witnessed such an enormous in- 

 crease in our knowledge of electricity. We must not, 

 in consequence of this fact, unduly exaggerate the im- 

 portance of the contributions of Franklin to electrical 

 knowledge nor underestimate the fundamental impor- 

 tance and magnitude of the advances made in electricity 

 since Franklin's time. 



