296 HYDROGEN AS A GAS AND AS A METAL. 



now, and in many more besides, for the purpose of the present lecture 

 we shall confine our attention to one of its most remarkable and widely 

 diffused compounds, viz, water. 



Water, in whatever condition we find it in nature, whether solid, liquid, 

 or gaseous, (as steam,) is a compound body, being made up of two sim 

 pie forms of matter — the one called oxygen, the principal constituent 

 of the air we breathe, and the otlier hydrogen. Chemists are acquainted 

 with several modes of breaking up the compound water into its two 

 elementary components ; but one of the most convenient methods we 

 can employ for effecting this analysis of water is to make electricity 

 tear asunder its two constituents. When water is made part of a gal- 

 vanic circuit, by plunging the two poles of a galvanic battery into a 

 vessel of the liquid, we find that bubl>]es of gas are evolved at eacli 

 pole. By a very simple arrangement, we can collect the gases given 

 off at each terminal of the battery, and we then find, on testing the 

 products, that two colorless gases are obtained, possessing widely dif- 

 ferent properties. We observe that the gas liberated at the end of the 

 wire connected with the platinum plate of the galvanic battery (the 

 positive pole) is colorless, heavier than atmospheric air ; and tliat when 

 a glowing wooden match is dipped into a vessel filled with the gas, the 

 wood burns with great brilliance, though the gas does not itself take 

 fire. This peculiar gas is therefore a powerful supporter of combustion, 

 though incombustible itself, and is called oxygen. We now turn our 

 attention to the gas given off at the negative pole of the battery, i. <?., 

 at that connected with the zinc plate. This is also found to be a color- 

 less gas, but very much lighter than air, and incapable of supporting 

 the combustion of a burning taper plunged into it ; but though not a sup- 

 porter of combustion in the ordinary sense of the term, it possesses the 

 remarkable property of burning itself with a pale lambent blue flame. 

 This is the gas hydrogen — the remarkable body whose chief properties 

 we have now more especially to study. 



[Other modes of liberating hydrogen from water were shown, and the 

 leading properties of the gas demonstrated.] 



When hydrogen burns in air, its sole product of combustion is water ; 

 hence the name of this remarkable substance, signifying " water-pro- 

 ducer." But oxygen and hydrogen can also be made to combine and 

 produce water when i)resented to each other in conditione nasccnti, or at 

 the moment of liberation from other forms of combination. The im- 

 portance of knowing this fact will be apparent further on. 



The beautiful researches of the late Professor Faraday have made us 

 familiar with the fact that manj^ of the gases known to chemists are 

 merely the vapors of extremely volatile liquids ; for, on subjecting 

 these gases to very great pressure and to intense cold, in many cases 

 liquids are obtained and even solids, which, on removal of the pressure 

 under which they were produced, resume the gaseous condition at ordi- 

 nary temperature. Hydrogen has been likewise subjected by the learned 



