446 On the polarized Condition ofPlatina 



tense green, having in the middle a red image equally intense 

 corresponding to the small square. This fact evidently de- 

 pends upon the same cause as the preceding one. 



1 shall terminate by a few words on the analogy admitted 

 by Sir David Brewster between accidental colours and har- 

 monic sounds. This philosopher considers as well as myself 

 the accidental colours as an impression spontaneously gene- 

 rated in the organ. Now, it is admitted in physics that the 

 harmonic sound has its origin in the sonorous body itself, 

 which, besides the principal vibration, executes accessory 

 ones. Moreover, the accidental impression continues after 

 the disappearing of the direct impression, and nothing of the 

 sort manifests itself with regard to harmonic sounds. The 

 analogy in question appears to me therefore very remote. 



The last objections that came to my knowledge have been 

 raised by Mr. Osann,in the journal of Mr. Poggendorff*. But 

 that article contains, with respect to my work, such inaccu- 

 racies, that they disfigure it and render it absurd : here is an 

 example, of which the reader may judge upon good grounds. 

 Mr. Osann describes in the following manner my experiment 

 on the combination of two complementary accidental co- 

 lours t : 



" Place on a black ground a I'ectangle of paper, the halves 

 of which are painted with two complementary colours, for 

 instance red and green, and each one marked in the middle 

 with a black point. If you look for some time at this coloured 

 rectangle, and afterixards shut your eyes completely^ there ivill 

 appear in its place a black image 'with a red point on o?ie side 

 and a green point on the other." 



I think it needless to extend further the examination of 

 this article, and to answer the objections therein contained. 



LXVII. On the polarized Condition of Platina Electrodes, and 

 the Theory of secondary Piles. By A Coiirespondent. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



AS so much interest has been lately excited by the peculiar 

 polarized condition into which platina electrodes may be 

 thrown, the following resuUs, obtained a few months since, 



* Annalen der Phijsik tmd Chimic, vol. xxxvii. 1836, p. 291, and fol- 

 lowing. 



t See at the beginning of my present article, on the subject of the 

 anonymous author's objections. 



