3 2 4 EXPERIMENTAL INVESTIGATIONS. 



a and b are two silver tubes four inches long by 0*3 inch dia- 

 meter ; they are joined by two platinum caps to a platinum 

 tube c t formed of a wire one-eighth of an inch diameter drilled 

 through its entire length, with a drill of the size of a large 

 pin ; a is closed at the extremity, and to the extremity of b 

 is fitted, by means of a coiled strip of bladder, the bent glass 

 tube d. The whole is filled with prepared water ; and having 

 expelled the air from a by heat, the extremity of the glass 

 tube is placed in a capsule of simmering water. Heat is now 

 applied by a spirit-lamp, first to b and then to a, until the 

 whole boils ; as soon as ebullition takes place the flame of an 

 oxyhydrogen blowpipe is made to play upon the middle part of 

 the platinum tube c, and when this has reached a high point 

 of ignition, which should be as nearly the fusing-point of 

 platinum as is practicable, gas is given off, which, mixed 



Fig. 10. 



with steam, very soon fills the whole apparatus and bub- 

 bles up from the open extremity either into the open air 

 or into a gas collector. Although by the time I had devised 

 this apparatus I was from my previous experiments tolerably 

 well assured of its success, yet I experienced a feeling of great 

 gratification when, on applying a match to one of the bubbles 

 which were ascending, it gave a sharp detonation ; I collected 

 and analysed some of it ; it was 07 oxyhydrogen gas, the resi- 

 due nitrogen, with a trace of oxygen. 



Those who have endeavoured to deprive water of air will 

 have no difficulty in accounting for the residual nitrogen, or 

 nitrogen mixed with a small portion of oxygen, which has 

 occurred in all my experiments. De Luc pointed out the im- 

 possibility of practically depriving water of air, and Priestley, 



