Metallic Bodies by Voltaic Electricity. 217 



was correctly determined by making the circuit with the large 

 copper wires pm, qrt, through the electrometer E alone, or 

 otherwise through a second electrometer set apart for that par- 

 ticular purpose. The wire mn being now included in the cir- 

 cuit, the effect on E was again examined, and, finally, the force 

 of the battery again observed as before; any error, therefore, 

 which might arise from a decrease in the power could be de- 

 tected and corrected by the addition of a small quantity of acid, 

 or by bringing a further portion of the battery into action ; the 

 variations, however, in this respect, for a short series of experi- 

 ments, were inconsiderable, and very easily rectified. The wire 

 in the electrometer E was about the ^5- th of an inch in diameter, 

 and was such that the indications on the scale corresponded very 

 nearly with the increased power when successive and equal por- 

 tions of the battery were immersed. The foUowing are a few of 

 the many interesting facts which seemed to be elicited by the 

 method of investigation. 



(z) When four wires, whose diameters varied from the Twth 

 to the T Vth of an inch, were successively placed in the circui , 

 as in m w, Fig. 3, the indications of the electrometer A with the 

 less perfect conductors, such as platinum and lead, seemed for 

 the most part in the ratio of these diameters : with the more 

 perfect conductors, such as silver and copper, the wires of the 

 lesser diameters only corresponded to the same ratio, whilst, on 

 the contrary, the smallest wires of the inferior conductors seem- 

 ed, as already shewn (7) to be in a great degree inaccessible to 

 the influence of the action. The following Table contains the 

 results of some experiments with a given charge on copper, pla- 

 tinum, and lead, three metals which appear to differ materially in 

 their conducting power. 



