HYDROGEN* 53 



portions, and mixing only one part of oxygen gas 

 with two of hydrogen. The report will then be 

 much louder than with common air. " 



This experiment may be made conveniently by 

 means of an apparatus called the inflammable air pis- 

 tol. To charge it, nothing more is necessary than to 

 introduce its mouth inverted into a wide-mouthed 

 bottle, filled with a mixture of oxygen and hydro- 

 gen gas, leaving it in for a few seconds ; it is then 

 to be stopped with a cork, and may be fired by the 

 electrical spark taken from the prime conductor of 

 the machine, or by a charged Ley den phial. 



' It has been, with great plausibility, conjectured, 

 that the noise of thunder is the effect of the rapid 

 combustion of hydrogen and oxygen gas, fired by 

 the electric spark ; and that the rain which falls so 

 copiously at the time of thunder-storms, is owing 

 to a sudden formation of water by this means. 



From its lightness, it has bqen employed for 

 making air-balloons, which have been already de- 

 scribed. 



Soap bubbles, filled with hydrogen gas, ascend 

 in the air. To show this, fill a bladder with hydro- 

 gen gas, and fasten it to a tobacco-pipe ; dip the 

 bowl of the pipe into a lather of soap, squeeze the 

 bladder gently, in order to form a bubble, and de- 

 tach it in the usual manner. These bubbles will 

 rise rapidly into the air : if a lighted taper be pre- 

 sented to them, they catch fire and burn with a 

 slight explosion. 



If the bladder be filled with a mixture of hydro- 

 gen and common air, the soap-bubbles will ascend, 

 and when the taper is presented to them they will 

 explode with a loud report. This experiment is 

 more striking if oxygen gas be mixed with 

 hydrogen. If the bladder be squeezed so as to 



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