CONSISTENT DIRECTION OF THE EVOLVED AND COMBINING BODIES. 447 



that their forces can consist with and compensate (in direction at least) the superior 

 forces which are dominant at the place where the action of the whole is determined. 

 If, for instance, in a voltaic circuit, the activity of which is determined by the attrac- 

 tion of zinc for the oxygen of water, the zinc move from right to left, then any other 

 cation included in the circuit, being part of an electrolyte, or forming part of it at the 

 moment, will also move from right to left ; and as the oxygen of the water, by its 

 natural affinity for the zinc, moves from left to right, so any other body of the same 

 class with it (i.e. any other anion), and under its government for the time, will move 

 from left to right. 



963. This I may illustrate by reference to fig. 11, the double circle of which may 

 represent a complete voltaic circuit, the direction of its forces being determined by 

 supposing for a moment the zinc b and the platina c as representing plates of those 

 metals acting upon water, d, e, and other substances, but having their energy exalted 

 so as to effect several decompositions by the use of a battery at a (989.). This sup- 

 position may be allowed, because the action in the battery will only consist of repe- 

 titions of what would take place between b and c, if they really constituted but a 

 single pair. The zinc b, and the oxygen d, by their mutual affinity, tend to unite ; 

 but as the oxygen is already in association with the hydrogen e, and has its inherent 

 chemical or electric powers neutralized for the time by those of the latter, the hydro- 

 gen e must leave the oxygen d, and advance in the direction of the arrow head, or 

 else the zinc b cannot move in the same direction to unite to the oxygen d, nor the 

 oxygen d move in the contrary direction to unite to the zinc b, the relation of the 

 similar forces of b and e, in contrary directions, to the opposite forces of d being the 

 preventive. As the hydrogen e advances, it, on coming against the platina c,y, which 

 forms a part of the circuit, communicates its electric or chemical forces through it to 

 the next electrolyte in the circuit, fused chloride of lead, g, h, where the chlorine must 

 move in conformity with the direction of the oxygen at d, for it has to compensate 

 the forces disturbed in its part of the circuit by the superior influence of those be- 

 tween the oxygen and zinc at d, b, aided as they are by those of the battery a ; and 

 for a similar reason the lead must move in the direction pointed out by the arrow 

 head, that it may be in right relation to the first moving body of its own class, 

 namely, the zinc b. If copper intervene in the circuit from i to /r, it acts as the 

 platina did before ; and if another electrolyte, as the iodide of tin, occur at /, m, then 

 the iodine /, being an anion, must move in conformity with the exciting anion, 

 namely, the oxygen d, and the cation tin m move in correspondence with the other 

 cations b, e, and h, that the chemical forces may be in equilibrium as to their direc- 

 tion and quantity throughout the circuit. Should it so happen that the anions in 

 their circulation can combine with the metals at the anodes of the respective electro- 

 lytes, as would be the case at the platina / and the copper k, then those bodies be- 

 coming parts of electrolytes, under the influence of the current, immediately travel ; 

 but considering their relation to the zinc b, it is evidently impossible that they can 



3 m2 



