VOLTAIC BATTERY. 



215 



FIG. 18. 



If in this arrangement the position of one of the metals 

 in the series be reversed, so that a zinc is where a copper 

 should be, then by the action of the acid on that zinc polariza- 

 tion in the wrong direction is occasioned, which greatly dimi- 

 nishes the general polarity of the circle, reducing it in an 

 arrangement of ten alternations to one fourth according to 

 Mr. Daniell. 



In the first of the two annexed diagrams (Fig. 18.) is re- 

 presented a com- 

 pound circle, such 

 as is employed to 

 produce decom- 

 position and call- 

 ed a voltaic bat- 

 tery, consisting of 

 three acid jars, 

 each of which con- 

 tains a zinc and 

 copperplate; and 

 which are termed active cells, as they are sources of polarizing 

 power, from the action of acid upon zinc which takes place 

 in them. 



In the second diagram (Figure 19), the same arrangement 

 FIG. 19. 



is repeated with the 'addition of a third jar, termed the de- 

 composing cell, which contains any polarizable liquid, with 

 two platinum plates immersed in it. Each copper, it will be 

 seen, is connected by a wire with the following zinc, and in 

 the first diagram, the copper in the third cell C" is imme- 

 diately connected with the zinc in the first cell Z by a wire, 

 and the circuit thus completed. The polar elements in the 



