86 CHEMICAL AFFINITY. 



though the result is the same in so far as it 

 gives us certain gaseous particles. Here then 

 is the hydrogen. I showed you yesterday cer- 

 tain qualities of this gas, now let me exhibit 

 you some other properties. Unlike oxygen, 

 which is a supporter of combustion, and will 

 not burn, hydrogen itself is combustible. There 

 is a jar full of it, and if I carry it along in this 

 manner, and put a light to it, I think you will 

 see it take fire, not with a bright light, you 

 will at all events hear it if you do not see it. 

 Now that is a body entirely different from oxy- 

 gen ; it is extremely light ; for although yester- 

 day you saw twice as much of this hydrogen 

 produced on the one side as on the other, by 

 the voltaic battery, it was only one eighth the 

 weight of the oxygen. I carry this jar upside 

 down. Why ? Because I know that it is a 

 very light body, and that it will continue in 

 this jar upside down quite as effectually as the 

 water will in that jar which is not upside down ; 

 and just as I can pour water from one vessel 

 into another in the right position to receive it, 

 so can I pour this gas from one jar into another 

 when they are upside down. See what I am 

 about to do. There is no hydrogen in this jar 



