428 M. P. Riess on the Generation of Heat by Electiicity. 



shank's battery of 36 pairs of 4-inch plates^ charged with water 

 containing ^^^rd. of a mixture of two measures sulphuric acid and 

 one measure nitric acid. From the bad conducting power of the 

 distilled water which formed a part of tlie circuit, the action was 

 slight. During the tirst half-hour similar minute quantities of 

 hydrogen were collected at the two negative poles. After 8f 

 hours' action, a decided difference in the quantities had become 

 apparent, there having been evolved from the negative pole in 

 the distilled water 0'04 cubic inch, and from the negative pole 

 in the acidulated water 0"07 cubic inch. After 24 hours, the 

 amounts were respectively 0"105 cubic inch and 0"2 cubic inch, 

 i. e. twice as much from the acidulated water as from the distilled 

 water. 



The only inference which I attempted to draw from such ex- 

 periments was, that the bad conducting power of the distilled 

 water interfered with the full electrolytic action. I confess that it 

 never once occurred to me that any inference could be drawn from 

 them, trenching upon the law of definite voltaic chemical agency j 

 nor does it yet appear to me that there is any foundation for 

 such an inference*. If M. Foucault's views be well founded, that 

 it follows from this and other experiments to which he refers, 

 that liquids have a conducting power independently of suffering 

 decomposition, and that in experiments such as the above, a 

 part of the current passes by this proper conduction, how is it 

 to be expected that the full decomposing effect should be pro- 

 duced ? It would be a violation of the law of definite agency if 

 the same amount of electrolytic action ensued, when a part of 

 the current passed by proper conduction, as when the whole 

 current passed in virtue of decomposing agency. There is 

 scarcely any law in science which does not present exceptions 

 and limitations, till we come to be able to ascertain the true 

 causes of such restrictions, when they by degrees return within 

 the limits of the general proposition. The histories of the rela- 

 tion between atomic weights and specific heats, of isomorphism, 

 and even of gravitation itself, afford illustrations of this principle. 



St. Antbcws, May 8, 1S54. 



LXIX. On the Generation of Heat by Electricity. By P. Riess. 

 To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



I REGRET exceedingly to find that Mr. Thomson, in the 

 Philosophical Magazine for May, page 347, while admitting 

 one error, has fallen into a new and more serious one, which I 



[* Oil reconsidering the subject our con-espondent may, perhaps, find 

 reason to change his opinion.— Ed.] 



