92 Mr. Grove on the Decomposition of Water hy Heat. 



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

 fitted, by means of o 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 h 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 

 with steam, very soon fills the whole apparatus and bubbles 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 1 experienced a feeling of great gratification 

 when on applying a match to one of the bubbles which were 

 ascending, it gave a sharp detonation ; 1 collected and ana- 

 lysed some of it; it was 0*7 oxyhydrogen gas, the residue 

 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 

 impossibility of practically depriving water of air, and Priest- 

 ley, from observing the obstinacy with which water retained 

 air, was led to believe that water was convertible into nitrogen 

 (phlogisticated air). I have repeated several of Priestley's 

 experiments under much more stringent circumstances, and 

 have never been able to free water from air, or so to boil 

 water that for every ebullition of vapour a minute bubble of 

 permanent gas was not left, which appeared to have been an 

 indispensable nucleus to the vapour. 



The difficulty of boiling water increases, as M. Donny has 

 proved, in proportion to its freedom from air, and at last the 

 bursts of vapour become so enormous that the vessels em- 

 ployed are generally broken. There appears to me a point 

 beyond which this resistance does not extend ; but even at 

 this point a minute bubble of air is left for each burst of va- 

 pour, though they are so few and distant that the aggregate 

 amount of gas is very trifling. I have produced from water 

 which had been previously carefully deprived of air by the 

 ordinary methods, three-fourths of its own volume of perma- 

 nent gas, which proved to be nitrogen ; but as the water in 

 this experiment was boiled under a long column of oil, it is 

 probable that if any oxygen were present, it might have been 



