portion on that side is thoroughly bleached—while nothing has apparently occurred on the other side. I say apparently, for you must not imagine that, because you cannot perceive any action, none has taken place.
Here we have another instance of chemical action. I take these platinum plates again, and 
Fig. 50.immerse them in this solution of copper, from which we formerly precipitated some of the metal, when the platinum and zinc were both put in it together. You see that these two platinum plates have no chemical action of any kind—they might remain in the solution as long as I liked, without having any power of themselves to reduce the copper;—but the moment I bring the two poles of the battery in contact with them, the chemical action, which is there transformed into electricity and
