660 



GROVE'S AND BUNSEN'S ELEMENTS. 



tage is the more important, as in many cases, which will be stated 

 later on, it is necessary, for obtaining the greatest effect, to pack as 

 much wire into a given small space as possible. 



About 100 grammes of uncovered wire, . l mm -5 thick, and 50 

 grammes of covered, O mm< 6 thick without the covering, will be 

 sufficient for the most important experiments. If more can be 

 afforded, a quantity of covered wire having a greater thickness 

 should be purchased. 



The galvanic current produced by our battery of six 

 copper-zinc elements is very feeble. Stronger currents, 

 however, may be produced by other combinations, for 

 example by Grove's or Bunserfs elements. In both of 



FIG. 339 A, B (A an. proj. ; A and B % real size}. 



them zinc forms the negative pole ; the positive pole is 

 formed in Grove's element by platinum, in Bunsen's by 

 carbon, or rather a hard, dense, and well-conducting 



