55 
Sir H. Davy’s researches on flame. 
oxygene, and heated the tube by a large spirit lamp till the 
volume of the gas was increased from i to 2.5. I then, by 
means of a blow pipe and another spirit lamp, made the 
upper part of the tube red hot, when an explosion instantly 
took place. 
I introduced into a bladder a mixture of oxygene and 
hydrogene, and connected this bladder with a thick glass 
tube of about ^ of an inch in diameter and three feet long, 
curved so that it could be gradually heated in a charcoal fur- 
nace ; two spirit lamps were placed under the tube where it 
entered the charcoal fire, and the mixture was very slowly 
pressed through : an explosion took place before the tube was 
red hot. 
This experiment shows that expansion by heat, instead of 
diminishing the combustibility of gases, on the contrary, 
enables them to explode apparently at a lower temperature, 
which seems perfectly reasonable, as a part of the heat com- 
municated by any ignited body must be lost in gradually rais- 
ing the temperature. I made several other experiments which 
establish the same conclusions. A mixture of common air and 
hydrogene was introduced into a small copper tube, having 
a stopper not quite tight ; the copper tube was placed in a 
charcoal fire; before it became visibly red an explosion took 
place, and the stopper was driven out. 
I made various experiments on explosions by passing mix- 
tures of hydrogene and oxygene through heated tubes ; in the 
beginning of one of these trials, in which the heat w r as much 
below redness, steam appeared to be formed without any 
combustion. This led me to expose mixtures of oxygene and 
hydrogene in tubes, in which they were confined by fluid 
