HYDROGEN. 201 



may also be obviated, by the substitution of a water- 

 pail, for the bowl represented in the figure. 



497. CHARGE OF AIR AND HYDROGEN. 



Describe an- 

 other explosive As air contains uncombmed oxygen, a 



mixture of air and hydrogen also forms an 

 explosive mixture. But, as air is only one-fifth oxy- 

 gen, five times as much of it must be used ; in other 

 words, five parts of air are required, for every two 

 parts of hydrogen. To make the mixture, hydrogen 

 may be led, as before, into an inverted vial, a little 

 more than two-thirds full of air. The exact propor- 

 tion is not essential in this, or any similar case of ex- 

 plosive mixture. 



498. A SIMPLER METHOD. A simpler 



Give a sim- ,-/., 



pier method method of loading the gun, or charging 

 ^ adin9the the vial with the explosive mixture, is to 

 invert it over a jet of hydrogen, as repre- 

 sented in the figure. The pipe-stem, or tube, 

 which conveys the gas, is previously wound 

 with paper, till it occupies about two-thirds of the 

 inner space of the gun. Escaping hydrogen fills 

 the remainder. On withdrawing the tube, air 

 enters to take its place, and the gun is thus 

 charged with mixed air and hydrogen, in the right 

 proportions. It is then corked and fired. This 

 experiment may also be made with a test-tube, 

 discharging it at the mouth. Explosions with mixed 

 air and hydrogen, are, of course, less violent than 

 where pure oxygen is used instead of the diluted oxy- 

 gen of the air. 



Docs hydrogen 499. HYDROGEN WILL NOT SUPPORT COM- 



support com- ' % . J .: ; 



bustion? BTTSTION. Flame is extinguished in hy- 



9* 



