402 TPNTH ANNUAL REPORT OF 



hyper-oxide attracts from the nearest molecule of water its hydrogeHj 

 and thus causes electrolysis throughout the whole liquid. 



To cover a platinum plate with hyper-oxide of lead, it is connected 

 with the positive pole of a battery of several pairs, whose negative pole 

 is connected with a similar platinum plate. The two plates are now 

 immersed in a solution of nitrate of lead, when the positive plate 

 is at once covered with a layer of super-oxide of the metal. 



The current which a polarized platinum plate yields with a clean 

 one, is, of course, transient ; it disappears with the electro-motive coat- 

 ing of the plate, and this is removed necessarily in consequence of the 

 formation oi the current. 



For example, let us consider a positive platinum plate polarized by 

 hydrogen ; this being combined with a clean platinum plate, a cur- 

 rent arises which passes from the coated to the clean plate ; thus, at 

 the coated plate, in consequence of the current, oxygen will escape, 

 and combine with the hydrogen which appears there. 



In like manner, the strata of chlorine, hyper-oxide of lead, &c., 

 with which the platinum plate has been negatively polarized, gradually 

 disappear, the chlorine or oxygen of the super-oxide combining with 

 the hydrogen escaping at this plate. 



Since platinum plates polarized by hyper-oxide are more strongly 

 electro-negative than clean plates, by combining plates of zinc and 

 platinum covered with hyper-oxide of lead, exceedingly powerful gal- 

 vanic batteries can be constructed. 



The practical application of such batteries is as yet opposed by the 

 fact that the stratum of super-oxide, the production of which is 

 somewhat troublesome, very soon disappears. 



Wheatstone has given us a measurement of the electro-motive force 

 of the hyper-oxide battery in the memoir already cited (Pog. Ann, 

 LXII, 522.) He found for the electro-motive force of — 



1. Zinc amalgam, sulphate of copper, copper 30 470 



2. Zinc amalgam, dilute sulphuric acid, copper 20 313 



3. Zinc amalgam, chloride of platinum, platinum... 40 626 



4. Zinc amalgam, dilute sulphuric acid^ platinum.... 27 423 



5. Potassa amalgam, sulphate of copper, copper.... 59 924 



6. Potassa amalgam, chloride of platinum, platinum 69 1081 



7. Potassa amalgam, sulphate of zinc, zinc 29 451 



8. Zinc amalgam, dilute sulphuric acid, hyper- 



oxide of lead 68 1065 



9. Potassa amalgam, dilute sulphuric acid, hyper- 



oxide of lead - 98 1535 



10. Zinc amalgam, dilute sulphuric acid, hyper- 



oxide of manganese 54 846 



11. Potassa amalgam, dilute sulphuric acid, by per- 



oxide of manganese 84 1316 



The first column of figures contains the values of the electro-motive 

 forces measured by revolutions of Wheatstone's rheostat ; the last 

 column gives the values reduced to chemical measure, assuming that 

 the electro-motive force of the first combination is equal to that of 

 Daniell's battery. 



