1156 The Galvanic Battery. [No. 108. 



be observed in the use of the Galvanic Battery : — *' Weak and exhausted 

 charges^ should never be used at the same time with strong and fresh 

 ones in the different cells of a trough, or the different troughs of a 

 battery ; the fluid in all the cells should be of the same strength, else 

 the plates in the weaker cells, in place of assisting, retard the passage 

 of the electricity generated in, and transmitted across the stronger cells." 

 " In the same manner, the association of strong and weak pairs 

 of plates should be carefully avoided." " The reversal^ by ac- 

 cident or otherwise, of the plates in a Battery has an exceedingly 

 injurious effect. It is not merely the counteraction of the current 

 which the reversed plates can produce, but their effect also in retarding, 

 even as indifferent plates, and requiring decomposition on their 

 surface in accordance with the course of the current, before the latter 

 can pass, is very deleterious. I find in a series of four pairs of plates 

 of zinc and platina in dilute sulphuric acid, if one pair be reversed, it very 

 nearly neutralizes the power of the whole." Another very serious 

 impediment to the full action of the battery, is the deposition of copper 

 on the surface of the zinc. This generally arises from the extensive 

 intermixture of the solutions in consequence of imperfections in the 

 partitions. Great attention ought therefore to be paid to keeping 

 these water-tight at their edges, so that intermixture may only take 

 place through the pores of the substance composing them. In my own 

 experience, I have occasionally found the entire igniting power of a 

 large twelve cell battery lost, from the preceding cause, and I find 

 Faraday repeatedly cautions us against it. 



Section IV. — Of Conductors — their nature^ uses, and modes of 



construction. 



When the Galvanic Battery is required to produce its igniting 

 effects at a distance, as is the case in all mining operations, a path 

 must be provided along which the generated current can find a ready 

 and uninterrupted passage. Such a path is best furnished by metallic 

 wires, the conducting power of the metals being very much superior 

 to that of any other class of substances. Of the metals, copper is 

 .invariably preferred, in consequence, of its high conducting power, its 



