VOLTAIC BATTERY. 267 



in contact with, and acting through the substance 

 of the membrane although unimmersed in any 

 fluid. Advantage was taken of this knowledge, 

 and it was contemplated that Potassium might, as 

 possessing such extraordinary affinities, also act 

 upon water through an intervening membrane. 

 Thus might its excessive action be moderated, and 

 itself rendered probably quiet and manageable. 



On the 5th of May last, the following plan 

 was ultimately adopted after much consideration, 

 and proved successful beyond my most sanguine 

 expectations. A wine glass was filled with dilute 

 sulphuric acid, and in this was immersed a plate 

 of platinum just below the surface of the liquid. 

 At the extremity of a short length of glass 

 tubing, a piece of membrane was tied, so as to 

 close up its lower end, which was by an appro- 

 priate stand so fixed, that the membrane, or 

 diaphragm, should come in contact with the surface 

 of the acidulated water, immediately above the 

 immersed plate of platinum. Into this tube was 

 dropped a globule of mercury, which, lying upon 

 the membrane, would serve to amalgamate, and 

 keep in that condition, the piece of Potassium 

 destined for this situation. The tube was then 

 filled with mineral naphtha, so that the metal 



