208 Mr. J. Goodman on a new and practical Voltaic Battery. 



tremity 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 

 appropriate 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 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 coining itself 

 in contact with the diaphragm. 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 potas- 

 sium became a very manageable clement in a voltaic battery ; 

 and on lowering it into contact with the diaphragm, a conti- 

 nuous current of 45° to 50° was observed by the aid of an in- 

 tervening galvanometer. To test the comparative power of 

 this arrangement with an ordinary pair, two plates, one of zinc 

 the other of copper, 1\ inches by If inch, were employed in 

 deflecting the same galvanometer. And it was found that in 

 very fierce action in water, strongly acidulated with sulphuric 

 acid, they only deflected the galvanometer to 65°, which in a 

 few minutes fell to 61°, although at that period in fair brisk 

 action. 



Potassium Experiment. — Aqueous Decomposition. 



. May 19, 1846. — Exp. 1. Again arranged this potassium 

 battery as before, substituting however solution of sulphate of 

 copper acidulated with sulphuric acid in the wine-glass. The 

 arrangement produced a remarkably quiet battery. The de- 

 flection of the galvanometer was but 10° to 30° when the de- 

 composition apparatus was connected. Two platina wire 

 poles, arranged as usual in acidulated distilled water in a con- 

 venient glass tube for showing the development of the gas, 



