258 HYDROGEN. 



by distending the lining membrane of the crop of the turkey, 

 which may weigh 35 or 36 grains, and when filled with hydrogen, 

 about 5 grains more, or 41 grains ; the same bulk of air, how- 

 ever, would weigh 50 or 51 grains; so that the little balloon 

 wKen filled with hydrogen has a buoyant power of 9 or 10 

 grains. Sounds produced in this gas were found by Leslie to be 

 extremely feeble, much more feeble indeed than its rarity com- 

 pared with air could account for. Hydrogen may be taken 

 into the lungs without inconvenience, when mixed with a large 

 quantity of air, being in no way deleterious ; but it does not, 

 like oxygen, support respiration, and therefore an animal placed 

 in pure hydrogen soon dies of suffocation. A lighted taper is 

 extinguished in this gas. 



Hydrogen is eminently combustible, and burns when kindled 

 in the air with a yellow flame of little intensity, which moistens a 

 dry glass jar held over it ; the gas combining with the oxygen of 

 the air in burning, and producing water. If before being kindled 

 the gas is first mixed with enough of air to burn it completely, 

 or with between two and three times its volume, and then 

 kindled, the combustion of the whole hydrogen is instantaneous 

 and attended with explosion. With pure oxygen instead of 

 air the explosion is much more violent, particularly when 

 the gases are mixed in the proportions of two volumes 

 of hydrogen to one of oxygen, which are the proper quantities 

 for combination. The combustion is not thus propagated 

 through a mixture of these gases, when either of them is 

 in great excess. The sound in such detonations is occasioned 

 by the concussion which the atmosphere receives from the 

 sudden dilatation of gaseous matter, in this case of steam, 

 which is prodigiously expanded from the heat evolved in its 

 formation. A musical note may be produced by means of these 

 detonations, when they are made to succeed each other very 

 rapidly. If hydrogen be generated in a gas bottle, and kindled 

 as it escapes from an upright glass jet having a small aperture, 

 the gas will be found to burn tranquilly ; but on holding an 

 open glass tube of about two feet in length over the jet, like a 

 chimney, the flame will be elongated and become flickering. A 

 succession of little detonations is produced, from the gas being 

 carried up and mixing with the air of the tube, which follow 

 each other so quickly as to produce a continuous sound or mu- 

 sical note. 



