514 Mr. G. Gore on 



of liquid was 4 inches in diameter and 1^ inch high, and consisted of 

 about 12 ounces by measure. The metals employed in this apparatus 

 were in nearly all cases either platinum, gold, or palladium.* 



The apparatus was made water-tight, by the aid of vulcanized india- 

 rubber washers ; but, as those washers affected the electric currents, 

 they were covered on each side by others of pure india-rubber, some- 

 what wider than themselves, secured to them by means of spirit- 

 varnish. In some cases, especially for the lower end of the cylinder, 

 where the heat did not affect them, washers of the pure rubber alone 

 were employed; and, for use with strongly alkaline solutions, the 

 vulcanized washers were, in certain instances, previously immersed 

 during five or six hours in a hot or boiling and strong solution of 

 caustic soda, to remove sulphur, and then thoroughly washed. Nearly 

 all the liquids were, previous to using, boiled, to expel dissolved air, 



* Messrs. Johnson and Matthey were kind enough to lend me a valuable pair of 

 palladium plates for these experiments. 



