Additional Notes. 395 



It is scarcely necessary to add, that tlic most able experimenters 

 on the subject of Galvanism are as unanimous in considering tlii» 

 fluid as an important cficmical agent. — '* Tliat a strong chemical 

 action takes place among the substances composing the pile of 

 -Volta is clearly proved, since one of tlic metals is always oxy dated, 

 and die sahne solution employed to moisten ihc paslcbo;ird i>> de- 

 composed 5 and that this action is intimately connected witli tJio 

 excitation of tlie electric energy-, is established by numeroas ex- 

 periments. The power of the apparatus ceasing when it is placed 

 in tlic exhausted receiver of tlie air-pump, or in a vessel lilJt-d 

 ■with azotic or hydrogen gas, strongly illustrates tiiis point. When 

 it is considered, also, that the apparatus is more powerful in 

 oxygen gas than in the atmospheric air, and that in eitlier the 

 oxygen is consumed ; and that its powers are much increased when 

 the water in contact with the metal, holds in solution oxygen, ni- 

 trous gas, diluted nitric or muriatic acid, or any substance which 

 either affords oxygen with fiicillty, or promotes the oxydation of 

 the metal, the evidence of strong chemical action will be viewed 

 as still more unquestionable. The power of the Galvanic series 

 or column seems, indeed, to be proportioned to the oxydation of 

 tlie metal which composes it; and hencfe it may, with much pro- 

 bability, be concluded, that it is to this chemical action tliat the 

 excitation. of the Galvanic influence is owing." 



Those who wish to see a more detailed account of tJie history 

 of Galvanism, especially of the numerous and verv^ interesting ex- 

 periments and discoveries made in this branch of phihKophy, in 

 ,tlie years 1801 and 1802, will do well tc^ consult tlie Philns. 

 Trans, for 1801, Tilloch's Philos. Mag., and Nichol,>,on's Jountal 

 of Natural Philosuphy. 



Note (I)y p. 37.— The theory of this celebrated pliilosopher 

 of St. Petersburg may be comprised in the following propo- 

 sitions. 



1. There exists a substance in all magnetic bodies, which may 

 be called the magnetic iluid ; the particles of which repd each 

 other with a force decreasing as tlie distances increase. 



2. The particles of mngnetic fluid attract and are attracted by 

 the particles of iron, with a force that varies according to the same 

 law. 



3. The piirticles of iron repel each othar acoiJing to tlie i>aine 

 law. 



