188 



OXYGEN. 



until the bell, B, is filled with water from the shelf of the pneumatic 

 cistern, on which, for this experiment, it must be placed. The 

 cock being closed, fill the bell, last mentioned, with oxygen gas, from 

 the cell of the cistern. Now lift the bell A, which may be easily 

 done, the pipe having a due flexibility, and introducing a candle, set 

 the bell again on the plate. Next exhaust the air until the candle 

 is nearly extinguished, and then open the cock, so as to allow the 

 oxygen to enter. The candle will now burn brilliantly for a much 

 longer time, than it had done, when the bell contained atmospheric 

 air." 



(e.) Ignited charcoal burns intensely in this gas, and the bark with 

 vivid scintillations. 



(f.) Iron wire or a watch spring, with a lighted sulphur match on 

 the end, burns with bright ignition and sparks, but without flame. 



Combustion of iron wire in oxygen gas. Id. 



11 Place over the cock of 

 one of the cells of the pneu- 

 matic cistern, sufficiently 

 supplied with oxygen gas, a 

 glass vessel, such as is usu- 

 ally employed to shelter can- 

 dles from currents of air. 

 Let the upper opening of 

 the vessel be closed, by a 

 lid with a central circular 

 aperture, as here represent- 

 ed. Leaving this aperture 

 open, by turning the key 

 of the cock, allow the gas 

 to rise into the vessel from 

 the cell. Next apply a ta- 

 per to the aperture, and as 

 soon as it indicates by an in- 

 creased brilliancy of com- 

 bustion, that oxygen has 

 taken place of the air pre- 

 viously in the vessel, cover 

 the aperture.* Wind a fine 

 wire round any hard cylin- 



* Or, any vessel, large or small, may be rilled with oxygen gas, by simply con- 

 veying the orifice of a curved tube to the bottom of the vessel, the other end of the 

 tube being connected with a gazometer or other reservoir, from which the gas is 

 allowed to flow ; the atmosphere is thus lifted out and the oxygen takes its place. 



