HYDROGEN. 



351 



A very pretty experiment may be made with a bladder full of hydrogen 

 gas. If a tube be fitted to the bladder already provided with a stop-cock, 

 and a basin of ordinary soap-suds be at hand, by dipping the end of the 

 tube in the solution and gently expressing the gas, bubbles will be formed 

 which are of exceeding lightness (fig. 341). They can also be fired with a 

 taper. 



Another experiment may be made with hydrogen as follows : If we 

 permit the gas to escape from the flask, and light it, as in the illustration, and 

 put a glass over it, we shall obtain a musical note, higher or lower, according 

 to the length, breadth, and thickness of the open glass-tube (fig. 342). If 



Fig. 338. Extraction of oxygen from air. 



a number of different tubes be employed, we can obtain a musical instrument 

 a gas harmonium. 



Hydrogen burns with a blue flame, and is very inflammable. Even 

 water sprinkled upon a fire will increase its fierceness, because the hydrogen 

 burns with great heat, and the oxygen is liberated. Being very light, H 

 can be transferred from one vessel to another if both be held upside down. 

 Some mixtures of H and O are very explosive. The oxyhydrogen blow-pipe 

 is used with a mixture of O and H, which is forciby blown through a tube 

 and then ignited. The flame thus produced has a most intense heating- 

 power. 



A very easy method of producing hydrogen is to put a piece of sodium 



