6 M. W. Beetz on the Excitation of Electricity 



Measurements executed with the positive electrode gave 

 indefinite results. The plates immediately became brown and 

 strongly negative, so that I obtained for the force Zn | Pd Q 

 values like 2*12 D. In correspondence with this, for the total 

 polarization Pd H | Pdo very great forces were found ; but I 

 convinced myself that their numerical evaluation was of no 

 importance, since here not the action of gaseous active or 

 passive oxygen comes into consideration, but that of the de- 

 posited layer of oxide. On this account, of the numerical 

 data obtained by other observers on the strength of the pola- 

 rization on palladium plates, \ can only compare one with 

 my own results : Graham*, namely, found that the polariza- 

 tion produced by from 1 to 4 Bunsen elements was 



Pd H | Pd = 1-50-1-85 D. 



I find, on electrolysis by 4 Grove or 6 Meidinger, 



1-83, 1-77, 



Mean ... Pd H | Pt o = l-80D ? 



therefore very nearly the same as Graham ; but the platinum 

 plate was not polarized to the maximum. A statement made 

 by Pearnellf , according to which the polarization 



Pd H | Pd = 0-306 D, 



is evidently much too low. 



Covering palladium with palladium-black made no alteration 

 in the polarization by hydrogen. BottgerJ gives proofs of the 

 powerful polarization of such blackened palladium plates; but 

 the prominent action comes into consideration only when the 

 closing of the current is continued, while with the momentary 

 closing required by the compensation method it is of no im- 

 portance. The palladium-black covering the positive electrode 

 is immediately pushed off; the layer of oxide which forms 

 completely exfoliates the black coating. 



Of other gases, I have caused chlorine, carbonic oxide, ethy- 

 lene, and sulphuretted hydrogen to act upon palladium. 



The action of chlorine commences with the first traces that 

 enter the fluid and are absorbed by it, and is strongly nega- 

 tive. When the fluid was saturated with chlorine there ap- 

 peared the electromotive force 



Zn | Pd, CI = 2-04 D; 



on the combination standing longer, the force certainly con- 



* Phil. Mag. [IV.] xxxviii. p. 243. 



t Ibid, xxxix. p. 52. % Jahresber. d. Frank/, ph. Ver. 1875-76, p. 23. 



