204 



HYDROGEN. 



It is plain from this experiment, that 

 hydrogen gas is a combustible, but not a 

 supporter of combustion ; it burns where 

 it is in contact with the air, but will not 

 permit a candle to burn in it ; on the 

 contrary, oxygen gas causes the candle 

 to burn more rapidly, but, when it is 

 withdrawn, the gas does not itself burn. 



(d.) Hydrogen gas burns in jets and 

 in many pleasing forms, as is illustra- 

 ted by the following figure. 



The bottle contains the materials to 

 afford the gas, which is kindled at the 

 orifice of the tube, (the common air 

 having been allowed previously to es- 

 cape,) and the jet is called the philo- 

 sophic candle. The flame is very pale, 

 but Dr. Hare, whose cut is annexed, 

 ascertained, that the addition of one 

 seventh of spirit of turpentine to the 

 materials, would " obviate this defect." 



(e.) If mingled with common air, 5 or 6 volumes, and hydrogen 

 gas 2, it explodes on contact with the flame of a candle. 



(/.) More violently with oxygen gas 1 part, and hydrogen 2, by 

 volume. This mixture should not be exploded in glass vessels, un- 

 less in small quantities, and unless the glass is strong, and well an- 

 nealed. It is better to use tubes of tin plate, or sheet copper ; a 

 cylinder of the latter, closed at one end ;* or two cones joined at the 

 base, and furnished with a mouth that can be corked firmly, and with 

 a touch hole, make a good discharging pistol. It is first filled with 

 water ; then with the mixed gases, and then kindled by a burning 

 candle, or sulphur match, applied at the touch hole.f Hydrogen gas 

 burns in volume with a yellowish flame, sometimes with points and 

 sparks of red. 



(g.) Hydrogen gas, from its levity,, escapes rapidly from vessels 

 held with their mouths upward ; but it remains a good while in con- 

 tact with the air, without escaping, if their mouths are in the reverse 



* If this mixture be allowed to escape from beneath water, the bubbles explode 

 violently on touching a flame at the surface ; a glass vessel should never be used in 

 this experiment. 



t If the double cone be filled with hydrogen and held with the mouth downward, 

 leaving the touch hole at the top open, the gas will slowly escape and may be kin- 

 dled, being gently pressed upwards by the atmosphere. If when partly burned, the 

 instrument be turned upwards, the mixed gases will explode. J. G. 



