22 REPORT—1840. 
sumes, according to my former experiments, a positive con- 
dition. It will hardly be necessary to mention, that heat also 
destroys the polarity in question. 
9. Oxygen obtained by the electrolysis of water, and deprived 
of its peculiar smell by the means indicated under § 5, has alto- 
gether lost its power of rendering gold and platina negative, and 
is, in a voltaic point of view, as inactive as oxygen prepared in 
the usual way. 
Phenomena of Polarization caused hy common Electricity. 
10. A gold or platina plate, having a perfectly clean and dry 
surface, assumes negative polarity when exposed to the action 
of a positive electrical brush issuing from a metallic or any 
other conducting point. The longer the brush is playing upon 
the surface of the metal, the higher will be the degree of polarity 
acquired by the gold or platina. A small platina stripe, after 
having been exposed to the action of a brush produced by 
thirty turns of my electrical machine, deviated the needle of a 
delicate galvanometer by 60°; sixty turns, under the same cir- 
cumstances, caused a deviation of 90°. It seems that the 
nature of the metal which performs the function of a point of 
emission also exerts some influence upon the degree of polarity 
acquired by gold and platina. Ceteris paribus, a point of 
emission consisting of gold caused a deviation of 170°, a point 
of brass only one of 60°. As to the metals (more readily oxid- 
able than gold or platina), I have only succeeded with silver 
and copper in polarizing them negatively by common elec- 
tricity. The degree of polarity acquired by the last-mentioned 
metals is, however, also exceedingly slight. 
11. The negative electrical brush produces exactly the same 
voltaic effects as the positive one does. 
12. A platina plate, polarized either by the positive brush or 
by the negative one, loses its electro-motive power when 
plunged only for a few moments into an atmosphere of hydro- 
gen. All the remarks made under § 8 also apply to the case 
in question. 
13. If gold or platina plates are connected with the prime 
conductor of an electrical machine, 7. e. made points of emis- 
sion, they will not assume any polar condition, however long 
and lively a brush may have been issuing from them. 
14. Heated or moistened gold, or platina plates, cannot be 
polarized by the electrical brush. 
15. If the points of emission are heated or moistened, the 
electrical brush issuing from them has no longer any polarizing 
power. It was impossible to excite in gold or platina even the 
