1874.] 



171 



[Outerbridge. 



Fifth column shows the amount of metal volatilized by each spark in 

 fractions of a grain troy. 



*Upper Pole. 

 Lower " 

 Upper *' 

 Lower " 

 Upper " 

 Lower " 

 Upper " 

 Lower " 

 Upper " 

 Lower " 

 Average. 



Gold 



16.6 

 16.7 



18.5 



Copper 



Gold Ingot, 24 



Tin 



Silver 



Lead 



30 



a 



24.8 

 25.1 

 91.6 



(( 



¥8 6000 



1 



325000 



_ 1 

 9T'S"^0 



_ 1 



1 9¥0000 



1 



121000 



Upper. 

 Lower. 

 Upper. 

 Lower. 

 Upper. 

 Lower. 

 jUpper. 

 Lower. 



Gold 20.5 



Copper 10 

 Gold Ingot 21 



Copper 20.2 



Silver 6 



Tin 20 



Nickel 12 



" 12 



1940000 



388 0000 



*NoTE — The upper pole usually formed the positive electrode. 



fNoTE— Them inimMOT of metallic Nickel producing a spectrum accordingto Cappel's 

 tables ig g^^ of a milligramme. 



