354 Mr. Faraday's Experimental Researches in Electricity. 



city, but unavailingly. In July last I received an anonymous 

 letter (which has since been published *,) describing a mag- 

 neto-electric apparatus, by which the decomposition of water 

 was effected. As the term " guarded points" is used, I sup- 

 pose the apparatus to have been Wollaston's (327. &c), in 

 which case the results did not indicate polar electro-chemical 

 decomposition. Signor Botto has recently published certain 

 results which he has obtained f; but they are, as at present 

 described, inconclusive. The apparatus he used was appa- 

 rently that of Dr. Wollaston, which gives only fallacious in- 

 dications (327. &c). As magneto-electricity can produce 

 sparks, it would be able to show the effects proper to this ap- 

 paratus. The apparatus of M. Pixii already referred to (343.) 

 has however, in the hands of himselff and M. Hachette§, given 

 decisive chemical results, so as to complete this link in the 

 chain of evidence. Water was decomposed by it, and the 

 oxygen and hydrogen obtained in separate tubes according to 

 the law governing volta-electric and machine-electric decom- 

 position. 



34-7. iv. Physiological Effects. — A frog was convulsed in the 

 earliest experiments on these currents (56.). The sensation 

 upon the tongue, and the flash before the eyes, which I at first 

 obtained only in a feeble degree (56.), have been since exalted 

 by more powerful apparatus, so as to become even disagree- 

 able. 



348. v. Spark. — The feeble spark which I first obtained with 

 these currents (32.), has been varied and strengthened by 

 Signori Nobili and Antinori, and others, so as to leave no 

 doubt as to its identity with the common electric spark. 



IV. Thermo-Electricity. 



349. With regard to thermo-electricity, (that beautiful form 

 of electricity discovered by Seebeck,) the very conditions under 

 which it is excited are such as to give no ground for expect- 

 ing that it can be raised like common electricity to any high 

 degree of tension ; the effects, therefore, due to that state are 

 not to be expected. The sum of evidence respecting its ana- 

 logy to the electricities already described, is, I believe, as fol- 

 lows: — Tension. The attractions and repulsions due to a 

 certain degree of tension have not been observed. In currents: 

 i. Evolution of Heat. I am not aware that its power of raising 

 temperature has been observed, ii. Magnetism. It was dis- 

 covered, and is best recognised, by its magnetic powers. 



* Lorul. and Edinb. Phil. Mag. and Journ. 1832, vol. i. p. 161. 



t Ibid. 1832, vol. i. p. 441. 



\ Annates de Chimie, li. p. 77- § Ibid. Ii. p. 72. 



