M. W. Beetz on the Magnitude of Galvanic Polarisation, 383 



acid, may probably be thus accounted for ; in the former case 

 the whole electrolyte is exactly decomposed into its constituents, 

 whilst in the latter case, besides the decomposition of water, a 

 separation of the sulphuric acid from the water also takes place, 

 consequently a second polarization occurs. 



On this account I endeavoured to obtain more of such decom- 

 positions, and employed for this purpose the haloid salts of the 

 alkaline metals, from which the halogens were separated at the 

 positive platinum electrode, whilst a plate of copper, immersed in 

 a solution of sulphate of copper, served as the negative electrode. 

 At the commencement I convinced myself that the same polariza- 

 tions occurred in these decompositions as in those of the hydrogen 

 acids. The following are the results : — 



Mean from VII. and VIII. =6-89 



In the decomposition of a sohition of iodide of potassium the 

 following values were obtained : — 



IX. 



Polarization, Pt (I). 



3-22 

 3-91 

 3-65 



Mean . . 3*59 



