268 THE POTASSIUM 



could be raised at pleasure into a medium in 

 which it would remain perfectly quiescent, and 

 would only suffer loss when required so to do. 



The Potassium, weighing about half a grain, 

 was now screwed upon the "tapped" extremity 

 of the copper wire, upon which a shoulder, or 

 button of wood, was also screwed, about one 

 sixteenth of an inch from its extremity, to 

 prevent the wire perforating the Potassium too 

 far, and coming itself in contact with the dia- 

 phragm. This wire was (as is usual) in metallic 

 communication with the immersed platinum, and 

 for the purpose of raising, or depressing the 

 Potassium in its cell, a moveable mercury cup 

 formed the medium of communication. From 

 this the Potassium hung suspended by its wire, 

 upon which a small weight was affixed, to ensure 

 the continuous contact and close application of 

 this metal to the membrane. 



With the apparatus thus arranged it was found 

 that Potassium became a very manageable ele- 

 ment in a voltaic battery ; and on lowering it into 

 contact with the diaphragm a continuous current of 

 45° to 50° was observed by the aid of an inter- 

 vening galvanometer. To test the comparative 



