CHEMICAL AFFINITY 4$ 



the vapor ascending into the vessel. And yet that is not 

 steam, for you know that if steam is brought near cold water, 

 it would at once condense, and return back again to water ; 

 this, then, can not be steam, for it is bubbling through the 

 cold water in this trough ; but it is a vaporous substance, and 

 we must therefore examine it carefully, to see in what way 

 the water has been changed. And now, in order to give you 

 a proof that it is not steam, I am going to show you that it 

 is combustible; for if I take this small vessel to a light, 

 the vapor inside explodes in a manner that steam could 

 never do. 



I will now fill this large bell-jar (F) with water; and I 

 propose letting the gas ascend into it, and I will then show 

 you that we can reproduce the water back again from the 

 vapor or air that is there. Here is a strong glass vessel (G), 

 and into it we will let the gas (from F) pass. We will 

 there fire it by the electric spark, and then, after the ex- 

 plosion, you will find that we have got the water back 

 again; it will not be much, however, for you will recollect 

 that I showed you how small a portion of water produced 

 a very large volume of vapor. Mr. Anderson will now 

 pump all the air out of this vessel (G), and when I have 

 screwed it on to the top of our jar of gas (F), you will 

 see, upon opening the stop-cocks (H H H), the water will 

 jump up, showing that some of the gas has passed into the 

 glass vessel. I will now shut these stop-cocks, and we shall 

 be able to send the electric spark through the gas by means 

 of the wires (I, K) in the upper part of the vessel, and you 

 will see it burn with a most intense flash. [Mr. Anderson 

 here brought a Leyden jar, which he discharged through 

 the confined gas by means of the wires (I, K).] You saw 

 the flash, and now that you may see that there is no longer 

 any gas remaining, if I place it over the jar and open the 

 stop-cocks again, up will go the gas, and we can have a 

 second combustion; and so I might go on again and again, 

 and I should continue to accumulate more and more of the 

 water to which the gas has returned. Now is not this 

 curious? In this vessel (C) we can go on making from 

 water a large bulk of permanent gas, as we call it, and 

 then we can reconvert it into water in this way. [Mr. 



