26 CORRELATION OF PHYSICAL FORCES. 



heat of friction, or mediately, by electricity resulting from mo- 

 tion, as in the electrical spark, which has most of the attributes 

 of solar light, differing from it only in those respects in which 

 light differs when emanating from different sources or seen 

 through different media ; for instance, in the position of the 

 fixed lines in the spectrum or in the ratios of the spaces 

 occupied by rays of different refrangibility. In the decom- 

 positions and compositions which the terminal points pro- 

 ceeding from the conductors of an electrical machine develope 

 when immersed in different chemical media, we get the pro- 

 duction of chemical affinity by electricity, of which motion is 

 the initial source. Lastly, motion may be again reproduced 

 by the forces which have emanated from motion ; thus, the 

 divergence of the electrometer, the revolution of the electrical 

 wheel, the deflection of the magnetic needle, are, when 

 resulting from frictional electricity, palpable movements re- 

 produced by the intermediate modes of force, which have 

 themselves been originated by motion. 



