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XIX. Theory of the Connexion between the Energy of Elec- 

 trical Waves or of Eight introduced into a System and 

 Chemical Energy, Heat Energy, Mechanical Energy, fyc. of 

 the same. By Meyer Wilderman. Pli.E)., B.Se. (Oxon.)*. 



IX the Philosophical Transactions of the Royal Society, 

 October 1902, the author published a paper " On Chemical 

 Dynamics and Statics under the Influence of Light." in the 

 appendix of which he indicated that the laws found experi- 

 mentally and communicated there find their rational basis and 

 explanation in thermodynamics. Here the author would like 

 to consider the subject in a more general and detailed manner, 

 not limiting himself to the results communicated there. 



A. General condition of Equilibrium of a System exposed 

 to Light or to Electrical Wares. 



The following considerations, the author believe.-, apply 

 to electrical waves and light simultaneously, for the reason 

 that both are aether waves with a great number of properties 

 in common. White light, as known, consists of light of 

 different wave-lengths, and though the action of light of dif- 

 ferent wave-lengths upon a chemical svstem is different in 

 a quantitative sense, the rays of different wave-lengths do not 

 differ from one another from the qualitative aspect. We do 

 not strictly speaking subdivide the different waves of the 

 spectrum according to their lengths into " chemical " and 

 "heat "rays. They all act " chemically, " and all produce 

 heat effects, and as far as the " chemical " effect is concerned 

 the maximum and minimum * ; chemical " effect will fall into 

 different places of the spectrum, depending not only upon the 

 wave-lengths of the light, but also upon the nature of the 

 chemical system itself. Sir William Abney showed that even 

 the red and ultra-red parts of the spectrum also possess the 

 property of producing chemical decomposition f. In the 

 same way, from the standpoint of the electromagnetic theory 

 of light, electrical waves are not to be separated into 

 a special category different from the light- waves — both 

 being aether-waves of the same fundamental nature. We 

 may safely expect that electric waves when introduced into 

 a chemical system are, as well as light-waves, capable 

 of producing phenomena connected with a variation of the 

 chemical potential, even if phenomena of chemical disso- 

 ciation or association, <fcc, may not be directly observed, and 

 that it will only be a matter of the proper choosing of the 



* Communicated by the Author. 



f Phil. Trans. Roy. Soc. 1880, ii. p. 60S. 



