Principles of Molecular Physics. 211 



their existence, and the entire range of molecular phenomena 

 cau be shown to be deduciblc from their fundamental properties 

 and relations to ordinary matter. 



Electric JEther. — My critic still cherishes the illusion that a dis- 

 crepancy or fallacy exists in my conception of the electric aether. 

 It is true that in my original memoir 1 hinted that the effective 

 mutual repulsion of the electric atoms might have its origin in 

 a repulsion between aethereal atmospheres condensed around 

 them by an attraction ; but in my reply to Professor Bay ma it 

 was distinctly averred that I did not advocate this doctrine, and 

 was only disposed to admit the possibility of its truth. If my 

 pertinacious critic is still disposed to run a tilt against it under 

 the hallucination that it is one side of my citadel, I can only look 

 upon his adventure with the same sort of interest with which we 

 contemplate the exploits of a knight-errant in a romance. 



I will take occasion in this connexion to remark that the con- 

 viction entertained by our author and other eminent physicists, 

 that the supposed electric fluid or sether is not to be regarded as 

 a vera causa in nature, appears to have its origin in certain mis- 

 conceptions or groundless assumptions. 



(1) It is deemed more philosophical to seek for the true origin 

 of electric and kindred phenomena in some mode of motion of 

 the ultimate parts of bodies, notwithstanding that the existence 

 of an sether (the luminiferous) having the same character of sub- 

 tilety and enormous energy of elastic force as the supposed elec- 

 tric sether is distinctly recognized. This is as much as if, after 

 Cavendish had discovered the properties of hydrogen gas, and 

 the phenomena exhibited by oxygen had been carefully studied, 

 it had been insisted that chemists must seek to explain these 

 phenomena by some imagined modification of the mechanical 

 condition of hydrogen, instead of attributing them to a new gas 

 having certain specific differences of property from oxygen. Why 

 should the hypothesis of a new sether similar to the luminiferous 

 be regarded as inherently less probable than several hypothetical 

 motions of the atoms or molecules of ordinary matter. 



(2) It is imagined to be a simpler conception to refer electric 

 phenomena to some mode or modes of motion of the atoms or 

 elements of bodies than to a new aether. Atoms may be con- 

 ceived to have any one of three different motions, viz. a vibra- 

 tory motion, a motion of rotation, or a motion of revolution. 

 Now let any one of these motions be hypothetically taken, and 

 the attempt made to obtain some glimpse of the manner in which 

 the phenomena might possibly evolve themselves. In the first 

 place, there must be two different motions answering to the posi- 

 tive and negative electric states. In the next place, these mo- 

 tions must be capable of propagation from molecule to molecule 



