21 G INDUCTIVE AFFINITY. 



circle of the first diagram, it will be found are six in number ; 

 namely, the three acid columns between the metals in the 

 cells, ab, cd and ef; and the three pairs of zinc and copper 

 plates, each of which forms a single polar element, of which 

 the surface of the zinc is the zincous, and the surface of the 

 copper, the chlorous pole. In the second diagram, one of 

 these metallic elements Z C" is divided, and a polarizable 

 liquid ffh, in the cell of decomposition, interposed between the 

 broken extremities PI and PI'. To ascertain the polar con- 

 dition of the extremities, or the terminal platinum plates in 

 the decomposing cell, it is to be observed that PP with Z 

 forms one polar element, of which Z being a zincous pole, PI' 

 must be a chlorous pole. Again, PI with C" forms one polar 

 element, of which C" being a chlorous pole, PI must be a 

 zincous pole. Now the platinum plates PI and PI' which 

 are thus zincous and chlorous, are disposed in the decomposing 

 cell, in regard to one another, the first to the left, and the 

 second to the right, as the zincous and chlorous plates, (the 

 zinc and copper), also are arranged in the active cells. It 

 will be convenient to distinguish, by names, the poles which 

 these terminal platinum plates constitute, as they are much 

 more frequently referred to, and of greater consequence than 

 any other poles in voltaic battery, when used as an instrument 

 of decomposition as it constantly is. The chlorous plate PI' 

 which is in connexion with a zinc plate Z, may be called the 

 chloroid (like chlorine, quasi- chlorine), and the zincous plate PI 

 which is connected with a copper plate C" may be called the 

 zincoid, (like zinc, quasi-zinc), names which express the virtual 

 properties of each plate, or the particular attractive power and 

 affinity which each of them acquires from its place in the circle. 



When hydrochloric acid is the polarizable liquid interposed 

 between these plates, chlorine is of course attracted by the 

 surface of the zincoid and discharged there, and hydrogen by 

 the face of the chloroid and discharged upon that plate. On 

 the electrical hypothesis, the same plates are variously denomi- 

 nated : 



The zincoid as the positive pole, the positive electrode, the 

 anode, and the zincode. 



The chloroid as the negative pole, the negative electrode, 

 the cathode and the platinode. 



The cell of decomposition thus interpolated in the voltaic 



