520 On Mr Faraday's Experimental Researches. 



was not known that the caustic alkalies arc hydra ts ; but as soon 

 as the fact was established, he opposed an hypothesis partly 

 founded on it, — that potassium and sodium are hydrurets, and 

 that the decomposition of water is essential to their formation. 

 His doctrine of the production of voltaic electricity was, — that 

 it is the result of the contact of bodies in different electrical 

 states, or becoming so on contact, acted on chemically by im- 

 perfect conducting agents interposed, to which water is not es- 

 sential ; and to this I would refer, declining entering further in- 

 to particulars against Mr Faraday's statements. 



In defending my brother, I would not wish to detract from 

 the real merits of Mr Faraday. In the papers in question, he 

 has brought forward much original information, and has made 

 us better acquainted with the powers of bodies in relation to the 

 conducting of electricity. And yet, even in this part of his 

 subject, he cannot be considered as just to my brother. My 

 brother had not only ascertained that certain bodies, as nitre, 

 the fixed alkalies, litharge, chlorate of potassa, from being non- 

 conductors in their solid state, became conductors on fusion, but 

 that the same property is possessed by earthy compounds and 

 oxides generally.* He had also found and pointed out many 

 bodies which are non-conductors when liquid, as sulphur, phos- 

 phorus, the combinations of these bodies and chlorine, the per- 

 chloride of tin, the chlorides of antimony and arsenic, the sul- 

 phuret of carbon, the chloride of azote,*)- and boracic acid. 



In Mr Faraday's augmented list of fluids which are non-con- 

 ductors, some of those bodies are mentioned as having been 

 tried by him, without reference to the labours of any former in- 

 quirers ; and, even on the fact of the loss of conducting power 



* " The alkalies and the earthy compounds and the oxides, as dry as we 

 can obtain them, though non-conductors when solid, are, on the contrary, all 

 conductors when rendered fluid by heat." — Phil. Trans. 1809, p. 101. 



f " The compound of chlorine and azote (he says) agrees with the com- 

 pounds of the same substance, with sulphur, phosphorus, and the metals, in 

 being a non-conductor of electricity."— Phil. Trans. 1813, p. 250. And, in an 

 earlier paper, he says, the liquid compounds of sulphur 3"d phosphorus and 

 chlorine " are non-conductors in the same degree as oils." — Phil. Trans. 1809, 

 p. 101.||Tn the same page, of boracic acid, he says, " it is a good conductor 

 as long as it contains water ; but freed from water, and made fluid by heat, 

 it is then a non-conductor." 



