On Mr Faraday* s Experimental Researches. 321 



on the conversion of water into ice, with which he opens his dis- 

 sertation (the fourth series), a fact on which the inquiry that 

 followed was founded, he speaks of it as a discovery of his own. ; 

 he makes no mention of any prior experiments on the subject; 

 not even of Franklin's.* Mr Faraday, in a note already given, 

 says Sir H. Davy was not aware of the general law he was then 

 engaged in developing ; that is, to use his own words, " the as- 

 sumption of conducting power by bodies as soon as they pass from 

 the solid to the liquid state. 1 ' Were this general, it might be ad- 

 mitted as a law ; but, as it is not, how is it a law ? My brother, 

 I have shewn (to confine myself to him), was acquainted with the 

 fact that certain bodies, and these not a few, acquired conduct- 

 ing power on fusion ; but, other bodies not doing so, it would 

 have been illogical to have deduced such a law. Mr Faraday's 

 new facts are valuable ; the law he has deduced from them does 

 not seem deserving of the name : it involves no general princi- 

 ple, — it insures no general results, — it throws no new light on 

 the conducting power. The most perfect conductors are metals 

 (whether solid or liquid, the form not being- apparently con- 

 cerned) ; diamond, and charcoal that has been well ignited, how 

 opposite are they in conducting power ! — how opposite the lat- 

 ter and common charcoal ! — but why, we know not. Till these 

 and other facts of a like kind are explained, attempts at the 

 formation of general laws on the subject can hardly fail of being 

 vain. 



I would willingly stop here, but I feel it incumbent on me to 

 proceed a little farther, to Mr Faraday's notice of my brother's 



• Franklin, in his suppositions and conjectures towards framing an hypo- 

 thesis for the explanation of the aurora borealis, has preceded Mr Faraday in 

 some of his conclusions. He says : iC 15. A certain quantity of heat wilTmake 

 some bodies good conductors that will not otherwise conduct. 



16. Thus wax rendered fluid, and glass softened, by heat, will both of 

 them conduct. 



u 17- And water, though naturally a good conductor, will not conduct well 

 when frozen into ice by a common degree of cold ; not at all when the cold is 

 extreme."— -Franklin's Works, 8vo, Lond. 1806, vol. ii. p. 'J I. 



And Bergman appears ultimately to have satisfied himself of the correct- 

 ness of Franklin's statement respecting ice, though he doubted it at first : he 

 was of opinion, says Priestley, " if he could procure plates of ice of a proper 

 thickness, he could charge them in the same mariner as glass."— 'Hist, of Elect. 

 part. i. p. 206. 4to edit. 



