HYDROGEN. 7 



owing to its power of absorbing gaseous and other 

 substances, itself being full of pores. 



Both the flame that we see in wood, and the bright 

 glow of coal fires, are owing to the burning of carbon; 

 the flames of candles, of oil lamps, of ordinary coal 

 gas, are all colored by the combustion of this substance. 

 It will soon be seen that it constitutes a very large 

 proportion in the organic part of all vegetables and 

 trees. 



Hydrogen, as I have said, is a gas, or kind of air. 

 It is transparent, tasteless, colorless and inodorous. 

 As we can not smell, taste or see it, we can only judge 

 of its properties by its action with other bodies. For 

 this purpose it is obtained by putting pieces of zinc 

 or iron filings into water, and then adding sulphuric 

 acid, that is, the common oil of vitriol. About a third 

 as much acid as water should be used. The mixture 

 will soon grow warm, and hydrogen gas will at once 

 commence rising to the surface in little bubbles. 



a. If a glass be laid upon the top of the tumbler 

 containing the mixture, so as to prevent the too rapid 

 escape of the gas, the tumbler will in a few moments 

 become so filled that the gas will burn when a flame 

 is brought into contact, with it. 



b. By far the most Flg t 

 satisfactory method is 



to conduct the opera 

 tion as represented in 

 fig. I. In the bottle 

 are placed the sul 

 phuric acid, zinc, and 

 water. The mouth of J 

 the bottle is stopped 



tightly by a cork, through which passes one end of the 

 tube a (this may be of glass or tin); the other end 

 passes under water in the cistern b, its course being 



