134 FARADA7 



and beauty of the experiment without the annoyance. The 

 copper which I have put into the flask will dissolve it : it will 

 change the acid and the water into a blue fluid containing 

 copper and other things, and I purpose then showing you how 

 this voltaic battery deals with it; and in the mean time we 

 will arrange another kind of experiment for you to see what 

 power it has. This is a substance which is to us like water 

 that is to say, it contains bodies which we do not know of 

 as yet, as water contains a body which we do not know as 

 yet. Now this solution of a salt( 16 ) I will put upon paper and 

 spread about, and apply the power of the battery to it, and 

 observe what will happen. Three or four important things 

 will happen which we shall take advantage of. I place this 

 wetted paper upon a sheet of tin-foil, which is convenient 

 for keeping all clean, and also for the advantageous applica- 

 tion of the power; and this solution, you see, is not at all 

 affected by being put upon the paper of tin-foil, nor by any 

 thing else I have brought in contact with it yet, and which, 

 therefore, is free to us to use as regards that instrument. 

 But first let us see that our instrument is in order. Here are 

 our wires. Let us see whether it is in the state in which 

 it was last time. We can soon tell. As yet, when I bring 

 them together, we have no power, because the conveyers 

 what we call the electrodes the passages or ways for the 

 electricity are stopped; but now Mr. Anderson by that 

 [referring to a sudden flash at the ends of the wires] has 

 given me a telegram to say that it is ready. Before I begin 

 our experiment I will get Mr. Anderson to break contact 

 again at the battery behind me, and we will put a platinum 

 wire across to connect the poles, and then if I find I can 

 ignite a pretty good length of this wire we shall be safe in 

 our experiment. Now you will see the power. [The con- 

 nection was established, and the intermediate wire became 

 red-hot.] There is the power running beautifully through the 

 wire, which I have made thin on purpose to show you that we 

 have those powerful forces; and now, having that power, 

 we will proceed with it to the examination of water. 



15 A solution af acetate of lead submitted to the action of the voltaic cur. 

 rent yields lead at the negative pole, and brown peroxide of lead at the posi- 

 tive pole. A solution or nitrate of silver, under the same circumstances, 

 yields silver at the negative pole, and peroxide of silver at the positive pole* 



