32 



DESCRIPTION OF GALVANIC BATTERIES. 



modification of Wollaston's Battery now in nse. Wollaston's bat- 

 tery is still generally used in large factories for depositing metals ; 

 and it is found by experience to be the most convenient and econo- 

 mical of all the batteries yet contrived. The modification we have 

 found to be very suitable, and practically useful, may be thus de- 

 scribed. In the arrangement represented above, when amalgamated 

 zincs are used, small quantities of amalgam fall from the zinc plates 

 upon the copper, which not only occasion local action, but the mer- 

 cury amalgamates with the copper, spreads over it, and to a great 

 extent lessens its efficiency ; and as the copper must be made red 

 hot to expel the mercury, much loss of copper as weU as mercury is 

 the result. To obviate this defect, the copper is connected above 

 the zinc and left open at bottom; as, for example, a thin sheet 

 of copper, of dimensions according with the size of the cells in the 

 battery, is cut thus : 



This copper is bent in the middle at >, the ends a a dip into the 

 cells, while c is bent over to connect with the zinc plate of the 

 neighbouring cell, thus 



10. 11. 



The zinc plates are placed between the bent copper a a. The fol- 

 lowing diagram of a battery of several pairs of plates will illustrate 

 these observations : 



xjp 



NJSW 



^ 



12. 



zzzz, The zinc plates, cccc, Copper plates, p 

 are generally made of thin wood, ww, Wires from 



which 



