PRESENT FUNDAMENTAL CONCEPTIONS OF PHYSICS. 511 



imparted to tliem in the production of the two kinds of electricity. The 

 other assumes that the electric condition of a body is caused by a dis- 

 turbed accumulation of freely acting aether. In accordance with the 

 latter view every nonelectric body would contain aether to a certain 

 amount. By the exciting of electricity (through friction, for example), 

 the equilibrium of the aether atoms and the ultimate particles of bodies 

 would be disturbed, and by reason of this a flowing over of the disen- 

 gaged aether from one body to another would take place; accordingly one 

 body would have uplus, the other a corresponding minus of the disen- 

 gaged cether ; one body then shows positive, the other negative elec- 

 tricity. Endeavors have been made to explain the electric current on 

 this ground. As yet neither the one nor the other representation has 

 succeeded in explaining all the fundamental phenomena in electricity, 

 although those observed up to the present time generally accord better 

 with the latter than the former. 



Although the hypotheses which aim at the ultimate attainment of a 

 common basis for the theories of light, heat, and electricity have not 

 satisfied the test in their detailed application, still the principle of the 

 conservation of energy in its application to the theory of electricity has 

 been found true. As every magnet may be considered the aggregate of 

 all its molecules, surrounded by electric currents, if the general electric 

 phenomena have been reduced to the theory of the conservation of en- 

 ergy, this reduction is, in principle, valid as to the primary magnetic phe- 

 nomena. 



As to Motional electricity an expenditure of work by friction is re- 

 quired in the separation of positive and negative electricity. The ex- 

 pended kinetic energy manifests itself on the rubbed bodies as the 

 potential energy of the separated electricities in this wise, the two 

 bodies which received the separated electricities strive to approach each 

 other. If this approach really takes place in easily moved bodies, as for 

 example in the motion of swinging electroscopes of opposite electricities, 

 it finally reappears as kinetic energy as manifested in the visible approach 

 of the easily moved electric carriers. The electric discharge in shape of a 

 spark, as also of heat, to which the electricity has been changed, shows 

 the passage and conversion from potential to kinetic energy. 



By means of electric machines mechanical energy is transformed to 

 the potential energies of positive and negative electricity. If the elec- 

 trically charged positive and negative conductors of an electric machine 

 are connected by a wire, the result is an electric current with which 

 mechanical, thermal, magnetic, chemical, and physiological effects may 

 be produced, with which therefore a transformation of energies may be 

 effected. 



The electric current also which emanates from galvanic batteries pro- 

 duces such transformations, in most cases to a higher degree than the 

 frictional electric current. If a given quantity of zinc is dissolved in 

 diluted sulphuric acid, which chemically is equivalent to its oxidation 



