52 



VOLTAIC BATTERIES. 



shall enclose a partition between them; by this means the 

 whole set may be at once lifted into or from the cells ; and thus 

 while the fluid remains in the trough, the action of the plates 

 may be suspended at pleasure. The form of this battery is 

 represented in the annexed diagram, Fig. 8. A further im- 



Fig. 8. 



provement in this form of battery was made by Wollaston. It 

 consists in doubling the copper plate, so as to oppose it to both 

 surfaces of the zinc, while the contact of the surfaces is pre- 

 vented by pieces of wood or cork placed between them. Ten 

 or twelve troughs on this construction form an efficient Voltaic 

 Battery. 



Smees Battery. Of all the galvanic batteries, however, now 

 in use, it will be found that the combination invented by 

 Mr. Smee, usually known as Smee's Battery, is the most useful 

 for medical purposes. It has the advantage of being tolerably 

 constant, sufficiently powerful for all cases, portable, easily 

 charged, and as easily cleaned. Its general plan is represented 



in Fig. 9. The battery consists of a plate 

 of platinized silver, connected with a binding 

 screw, and fixed to a beam of wood. A strip 

 of stout and well amalgamated zinc is placed 

 on each side of the wood, and both are held 

 in their place by a binding screw, sufficiently 

 wide to embrace the zinc and the wood. 

 This arrangement is immersed in a cell 

 containing diluted sulphuric acid, made by 

 mixing together one part by measure of 

 sulphuric acid and seven of water. The 



Fig. 9. 



