136 FARADAY 



dipped into the solution], this, you see [exhibiting one of the 

 platinums], is at once turned into copper, as it were; it 

 has become like a plate of copper; and that [exhibiting the 

 other piece of platinum] has come out quite clean. If I 

 take this coppered piece and change sides, the copper 

 will leave the right-hand side and come over to the left 

 side; what was before the coppered plate comes out clean, 

 and the plate which was clean comes out coated with cop- 

 per; and thus you see that the same copper we put into 

 this solution we can also take out of it by means of this 

 instrument. 



Putting that solution aside, let us now see what effect this 

 instrument will have upon water. Here are two little plati- 

 num plates which I intend to make the ends of the bat- 

 tery, and this (C) is a little vessel so shaped as to enable 

 me to take it to pieces, and show you its construction. In 

 these two cups (A and B) I pour mercury, which touches the 

 ends of the wires connected with the platinum plates. In 

 the vessel (C) I pour some water containing a little acid (but 

 which is put in only for the purpose of facilitating the 

 action; it undergoes no change in the. process), and con- 

 nected with the top of the vessel is a bent glass tube (D), 

 which may remind you of the pipe which was connected with 

 the gun-barrel in our furnace experiment, and which now 

 passes under the jar (F). I have now adjusted this appara- 

 tus, and we will proceed to affect the water in some way or 

 other. In the other case I sent the water through a tube 

 which was made red-hot; I am now going to pass the elec- 

 tricity through the contents of this vessel. Perhaps I may 

 boil the water ; if I do boil the water I shall get steam ; and 

 you know that steam condenses when it gets cold, and you 

 will therefore see by that whether I do boil the water or not. 

 Perhaps, however, I shall not boil the water, but produce 

 some other effect. You shall have the experiment and see. 

 There is one wire which I will put to this side (A), and here 

 is the other wire which I will put to the other side (B), and 

 you will soon see whether any disturbance takes place. Here 

 it is seeming to boil up famously; but does it boil? Let us 

 see whether that which goes out is steam or not. I think you 

 will soon see the j&r (F) will be filled with vapor, if that 



