M. W. Beetz on the Magnitude of Galvanic Polarization, 381 



mined the charge of two platinum plates between which hydro- 

 chloric acid was decomposed. In these experiments either both 

 electrodes consisted of platinum, in which case the polarization 

 Pt(Cl) + Pt(H) had to be subtracted from the original force of the 

 current, or the positive plate consisted of zinc, and was immersed 

 in a solution of sulphate of zinc, when the polarization Pt(H) alone 

 remained ; or lastly, the negative plate consisted of copper and 

 was immersed in a solution of sulphate of copper, in which case 

 the polarization was Pt(Cl). In the last two cases the force of 

 a second battery was introduced into the circle ; that is, Pt CI H 

 -f ZnO SO^ in the one case, and Cu SOHPt CIH in the other. 

 These forces were measured by the compensation-method, and 

 then introduced into the calculation with their proper signs. 

 For the sake of convenience, all the electromotive forces which 

 will be employed in the following experiments are collected 

 together in the following table. According to the unit here 

 employed, the force of a Grovels battery was found from a mean 

 of twelve measurements to be 37'26. 



I. 



rix^ 



PtSO^ =40-26 

 PtNO^ =36-24 

 PtS03Aq= 32-66 

 PtKCl =31-97 

 PtNaCl =31-80 

 PtNaBr =30-79 



PtKBr =29-50 

 PtClH =29-10 



PtKI =21-67 



CuCuO 80^=21-22 

 ZnZnOS03= 1-34 

 ZnSO^Aq = 



These numbers are for the most part deduced immediately 

 from measurement, and partly by employing the law of the elec- 

 tromotive powers of bodies to the actual measurements. At 

 first, the circuit of a battery of platinum and zinc, consisting of 

 one or more elements, was closed by means of two platinum 

 plates in hydrochloric acid. By measuring the force of the bat- 

 tery alone, and its force after introducing the hydrochloric acid, 

 the following six values were successively obtained for the — .^ 



II. ^ 



Polarization, Pt (CI) -hPt (H). 



29-30 

 27-91 

 30-29 

 30-32 

 27-45 

 27-75 



Mean . . 28-83 



