HYDROGEN. 



203 



(d.) Balloons* are filled with it. The principle of balloons is very- 

 well exhibited by filling soap bubbles with hydrogen gas, or, better still, 

 with the explosive mixture of oxygen and hydrogen ; they will rise in 

 the atmosphere ; the former rapidly, the latter more quietly, and the 

 flame of a candle will fire them as they pass ; in the latter case there is 

 a considerable explosion. The solution of soap should be strong, and 

 used cold, and a metallic pipe will allow the bubbles to be more easily 

 disengaged than one of clay. If a dish of strong soap water be blown 

 up full of bubbles of the mixed gases, it detonates powerfully, when fir- 

 ed by throwing a burning match into it. A bladder, filled in the same 

 manner, may be fired by piercing it with a sharp wire, fixed to a pole, 

 and having, appended to the wire, a burning rag moistened with spirit 

 of turpentine. 



(e.) Musical tonesf are produced when a small jet of this gas is 

 burned in a glass or other tube. They are produced also by car- 

 bonic oxide, coal gas, olefiant gas, and vapor of ether, burning in a 

 jet ; the sounds are produced in bottles, flasks, and vials ; and globes, 

 from seven to two inches in diameter, give very low tones. The re- 

 port is considered by Mr. Faraday, agreeably to the views of Sir 

 H. Davy, as only a continued explosion. J 



5. CHEMICAL PROPERTIES. 



(a.) Hydrogen possesses extensive powers of com- 

 bination, as will be seen in the history of other bo- 

 dies, especially of chlorine, iodine, sulphur, carbon, 

 &c., and of animal and vegetable substances. 



(6.) ITS INFLAMMABILITY IS ITS MOST IMPORT- 

 ANT PROPERTY. 



(c.) A candle kindles a jar of it, but is itself ex- 

 tinguished by immersion in the gas, and is relighted 

 if the wick again touch the flame ; see the an- 

 nexed figure of Dr. Hare, which needs no explana- 

 tion. 



* For some curious and amusing speculations respecting the possible uses of bal- 

 loons, see the Am. Jour. Vol. XI, XII and XIII. Gay Lussac, who ascended till the 

 mercury in the barometers stood at 11 inches, ascertained, that magnetism and elec- 

 tricity existed at that height, in undiminished energy, and that the proportion of 

 oxygen and nitrogen, was the same as at the surface of the earth. 



t A. jet of flame from one of the gazometers, p. 184, is admirably adapted to insure 

 the success of this pleasing experiment. By turning the key, the jet is accurately 

 regulated, and a great variety of tones, from the most acute to the most grave, is 

 easily produced by using tubes of different materials, diameters, length and thick- 

 ness; hardly any "tube comes amiss, and the same tube will give a variety of tones, 

 if moved up and down, while the flame is in it. 



t Eng. Jour, of Science, No. 10. 



