Skey. — Action of Potass mm-Ci/a7iide upon Gold. 713 



have, that there is oxidation going on at the surface of the gold 

 in vessel C, Fig. 1 (oxidation of potassium), simultaneously 

 with the cyanodizing of the gold in vessel A, I have weakened 

 the strength of my argument that the gold A in the strong 

 cyanide is the positive element of the voltaic pair which is 

 produced in this apparatus. In such a case I would answer 

 him by stating that the free oxygen at this pole (the gold F) 

 simply takes the place of the combined oxygen of the potash 

 next to it, pushing that atom of oxygen on to another atom of 

 potash to the displacement of its particular atom of oxygen, 

 and so on till the chlorine is reached, when this radical is 

 pushed on in like manner till cyanogen is reached, which in 

 its turn is slid on, as it were, till the last atom of it in the line 

 of action collides with the gold, and a chemical effect then and 

 there takes place that is productive of the electromotive power 

 that we find. The gold at tliat point thus shows itself to be 

 the positive element of the apparatus, which is in strict ac- 

 cordance with the law that it is always the metal that is 

 attacked which determines the direction of the current. But 

 I maintain that daring these actions never is any atom or 

 fraction of an atom of either oxygen or cyanogen at any time 

 absolutely freed from all combinations ; it is, as it were, a 

 waltz in which the dancers are ever changing partners, but 

 not one of them is ever clear of a partner — that is, never in a 

 state of isolation. 



In regard to this matter, I would state here that lead in 

 strong soda solutions, like gold in strong "cyanide" solu- 

 tions, is oxidized and dissolved far quicker when only partly 

 immersed than when wholly immersed therein. Like gold 

 in cyanide solutions, lead is also iriore soluble in weak 

 potash solutions than in its strong solutions. Lead in 

 a strong pota.sh solution is weakly positive to lead in 

 a weak potash solution, but becomes more positive when 

 the other piece of lead is placed in nitric acid, and so 

 becomes rtipidly dissolved. In these cases I also suppose 

 the aerial oxygen takes the place of the oxygen of the potash 

 next to it, and the sliding process goes on till the lead is 

 reached, when strong chemical action takes place. 



That the positive pole should be that at which the least 

 chemical action takes place seems inexplicable until we con- 

 sider that the direction of the current is here determined by 

 intensity, not by quantity ; and the current that is produced 

 by the lead in the potash solution is more intense than that 

 produced by the lead in the nitric-acid solution, because (in 

 part at least) free oxygen of the air is the exciting agent in 

 that case, while in the case of the acid solution a combination 

 has to be broken up for the oxidation of the lead, which, of 

 course, involves a lessening of electric intensity of the current 



