THE SMITHSONIAN. INSTITUTION. 401 



necting the two plates, because the hydrogen of tlie gold pLate is not 

 in the condition to attract the oxygen of the nearest particle of water, 

 and thus to produce electrolysis throughout the whole stratum of 

 liquid; but if platinum be used instead of the gold plate, the peculiar 

 relation of this metal to hydrogen and oxygen induces electrolysis by 

 causing the hydrogen nearest the platinum phitc to attract the oxygen 

 from its neighboring particle of water, and thus the decomposition 

 and recomposition of water extends to the other plate. Tims it is 

 sliowu why the experiment No. 1 succeeds with platinum plates^, but 

 not with gold or silver. 



Schonbein considers it not improbable that this action is produced 

 hy a sub-oxide of hydrogen, the hydrogen of which has a greater de- 

 oxidizing force than pure hydrogen, as the third atom of oxygen of 

 the super-oxide shows a greater affinity for oxidable bodies than pure 

 oxygen. 



A platinum plate immersed in chlorine gas, combined voltaically 

 with a clean one in dilute sulphuric acid, yields a current, because, in 

 this combination, the atlinity of the chlorine is sufficiently strong to 

 attract the hydrogen from the nearest molecule of water, and form 

 hydrochloric acid ; hence the electrolysis of the water is induced all the 

 way to the other plate. Even if gold and silver plates be used in this 

 experiment, the chlorine has the power of decomposing water ; hence, 

 in this case, the current which passes, of course, in the direction in 

 %vhich the particles of hydrogen go, continues until the chlorine on 

 one of the plates disappears. 



The formation of the current in experiment No. 3 is to be explained, 

 in a manner entirely analogous to this. 



But, by using pure oxygen instead of chlorine or bromine^ in the 

 above combination, it is not found in such a state of activity, to use 

 Schonbein' s language, as to cause the decomposition of the nearest 

 particle of water ; hence the absence of the current in the experiments 

 No. '1 (in section 39,) and No. 2 (in section 40.) 



But if pure oxygen in this case cannot excite a current of polariza- 

 tion, how is the negative polarization of a platinum plate, which has 

 served as a positive electrode, to be explained ? Certainly not by the 

 oxygen evolved at its surface. Ozone, as well as oxygen, escapes at 

 the pt3sitive electrode, and that this remarkable body can j)olarize 

 platinum plates negatively has been stated. 



According to Schonbein, ozone is a super- oxide of hydrogen ; a 

 view w^hicli is strongly supported by the fact that the super-oxides ot 

 metals have a precisely similar voltaic action. The third atom of 

 oxygen has a greater affinity for oxidable bodies than free oxygen, 

 and thus the strong electro-negative action of these substances is ex- 

 plained. 



§ 42. Hijper-oxide hatteries. — A platinum plate, covered with a hy- 

 per-oxide, as, for instance, hyper-oxide of lead, acts electro-negatively 

 towards a clean platinum plate. On immersing the two plates con- 

 nected with the terminal wires of a multiplier, in dilute sulphuric 

 acid, a powerful current arises, passing from the clean plate to the 

 one covered with the hyper-oxide. The third atom of oxygen in the 

 26 



