120 



CHEMISTRY. 



Fig. 43. 



150. Hydrogen not a Supporter of Combustion. Though 



hydrogen burns, it does not support combustion. 

 This may be shown by the following experiment : 

 Let there be introduced into the bell-jar, a, Fig. 43, 

 filled with hydrogen, a lighted taper. It will set 

 the hydrogen on fire at the mouth of the bell-jar, 

 but will itself go out as soon as it is immersed in 

 the gas. If you take it immediately out, it will be 

 relighted as it passes through the burning hydrogen at the 

 mouth of the glass jar, and the putting out and relighting 

 may be repeated several times in succession. 



151. Production of Musical Sounds. If you let a "philo- 

 sophical candle " burn in a tube, as seen in Fig. 44, mu- 

 sical sounds will be 

 heard, which will 

 be varied in their 

 note by the size of 

 the tube, and by 

 raising or lowering 

 it. The sound is ow- 

 ing to the vibra- 

 tion of the air con- 

 fined in the tube, 

 caused by the burn- 

 ing of the hydrogen. 

 This experiment is 

 not peculiar to hy- 

 drogen, but may be 

 made with a small jet 

 of coal gas. In the 

 first -named form it 

 is sometimes called 



" Ha rmonica che- 



Fig.44. mica" 



