Influence of Convection on Rotatory Polarization. 367 



liberated) now gave considerably higher currents than before 

 the electrolysis, in some cases twice the current, while the 

 positive electrode gave the same current as before. On first 

 charging up the negative electrode positively, there was 

 frequently a very large current for a short time, which was 

 not repeated on the second charging, as if there were some 

 positive ions loosely attached to the electrode which got 

 driven away ; the smaller increase to which I have alluded 

 lasted for about half-an-hour. The amount of the increase 

 varied a good deal ; in one or two experiments there was no 

 change in the current. The experiments with liquid electro- 

 lytes are more ambiguous than those with gases, as there is 

 the possibility of some acid adhering to the plate and not 

 getting entirely removed by the washing and drying, and 

 then setting up some chemical action. Against this explana- 

 tion we have the fact that the increase only occurs with one 

 electrode — the negative, not with the positive — so that if it 

 is due to the chemical action it must be caused by something 

 produced at the negative terminal and not at the positive. 

 Hydrogen peroxide seemed to me the most likely substance, 

 so I immersed a platinum plate in a strong solution of H 2 2 , 

 and washed and dried it in the same way as the electrodes. I 

 found, however, in this case no change in the current through 

 the tank B. 



I have much pleasure in thanking my assistant, Mr. E. 

 Everett, for the help he has given me in these experiments. 



June 1902. 



XL. On the Influence of Convection on Optical Rotatory 

 Polarization. By J. Laemor *. 



THE postscript (this volume, p. 220) to Lord Rayleigh's 

 account of bis decisive determination that the orbital 

 motion of the Earth is without influence on the rotatory pola- 

 rization produced by quartz, has brought to my notice the 

 recent paper by Prof. H. A. Lorentz there quoted. 



The fundamental character of Lord Rayleigh's negative 

 result may be illustrated by reference to Prof. LoremVs 

 Versuch einer Theorie . . ., p. 119 (1895), where the opposite 

 conclusion is considered as not unlikely in view of the formal 

 possibilities that are open. But the main object of this note 

 is to entirely admit the demur made by Prof. Lorentz, that 

 my criticism (-.Ether and Matter/ p. 214) of his calculation 

 of rotational effect, there given, is not well founded. The 

 conclusion which I had reached was in fact that for light 

 of given absolute wave-length the optical rotation would be 



* Communicated by the Author. 



