GALVANIC INSTRUMENTS. 

 Fig. 336. 



327 



support them at the ends, any fluid which may be in one 

 trough must flow into the other, and, reversing the move- 

 ment, must flow back again. The galvanic series being 

 placed in one of the troughs, and the acid in the other, by a 

 movement such as has been described, the plates may all be 

 instantaneously subjected to the acid or removed from it ; 

 the pivots are made of iron, coated with brass or copper, as 



