Dr. Hare's Second Letter to Prof. Faraday. 473 



trical induction obey the same law as respects the influence 

 of distance upon the respective intensities. 



59. From these considerations, and others above stated, I 

 infer, that if electrical induction were an action of particles in 

 proximity, operating reciprocally with forces varying in in- 

 tensity with the squares of the distances, their aggregate 

 influence upon any surfaces, between which they might be 

 situated, would be proportionable to their number; and since 

 experience demonstrates that the inductive power is not di- 

 minished by the reduction of the number of the intervening 

 particles, I conclude that it is independent of any energy of 

 theirs, and proceeds altogether from that electrical accumula- 

 tion with which the inductive change is admitted to originate. 



60. In paragraph 31, you say, " that at one time there was 

 a distinction between heat and cold. At present that theory 

 is done away with, and the phfenomena of heat and cold are 

 referred to the same class, and to different degrees of the 

 same power." 



61. In reply to this I beg leave to point out, that although, 

 in ordinary acceptation, cold refers to relatively low tempe- 

 rature, yet we all understand that there might be that perfect 

 negation of heat, or abstraction of caloric, which may be de- 

 fined absolute cold. I presume that, having thus defined 

 absolute cold, you would not represent it as identical with 

 caloric. For my own part, this would seem as unreasonable 

 as to confound matter with nihility. 



62. Assuming that there is only one electric fluid, there 

 appears to me to be so far an analogy between caloric and 

 electricity, that negative electricity conveys, in the one case, 

 an idea analogous to that which cold conveys in the other. 

 But if the doctrine of Du Fay be admitted, there are two 

 kinds of electric matter, which are no more to be con- 

 founded than an acid and an alkali. Let us, upon these pre- 

 mises, subject to further examination your argument (1330), 

 that insulation and conduction should be identified, ^^ since 

 the moment we leave in the smallest degree perfection at either 

 extrcmitij, we involve the element of' peijection at the opposite 

 end" Let us suppose two remote portions of space, one re- 

 plete with pure vitreous electricity, the other with pure resin- 

 ous. Let there be a series of like spaces, containing the resin- 

 ous and vitreous electricities in as many different varieties of 

 admixture, so that in passing from one of the first-mentioned 

 spaces, through the series to the other, as soon as we should 

 cease to l)e exposed to the vitreous fluid, in perfect purity, we 

 sht)uld begin to be exposed minutely to the resinous; or that, 

 in passing I'rom the purely resinous atmosphere, we should 



