6q Sir H. Davy's researches on flame. 
pally depend upon the power they possess of rapidly abstract- 
ing heat from the contiguous particles ; and this will depend 
probably upon two causes, the simple abstracting power by 
which they become quickly heated, and their capacity for 
heat which is great in proportion as their temperatures are 
less raised by this abstraction. 
Whatever be the cause of the different cooling powers of 
the different elastic fluids in preventing inflammation, very 
simple experiments show that they operate uniformly with 
respect to the different species of combustion, and that those 
explosive mixtures, or inflammable bodies, which require 
least heat for their combustion, require larger quantities of 
the different gases to prevent the effect, and vice versa ; thus 
one of chlorine and one of hydrogene still inflame when 
mixed with eighteen times their bulk of oxygene, whereas a 
mixture of carburetted hydrogene and oxygene in the proper 
proportions for combinations, one and two, have their inflam- 
mation prevented by less than three times their volume of 
oxygene. 
A wax taper was instantly extinguished in air mixed with 
of silicated fluoric acid gas, and in air mixed with £ of 
muriatic acid gas ; but the flame of hydrogene burned readily 
in those mixtures, and in mixtures in which the flame of 
hydrogene was extinguished, the flame of sulphur burned. 
There is a very simple experiment which demonstrates in 
an elegant manner this general principle. Into a long bottle 
with a narrow neck introduce a lighted taper, and let it burn 
till it is extinguished ; carefully stop the bottle, and introduce 
another lighted taper, it will be extinguished before it reaches 
the bottom of the neck : then introduce a small tube contain- 
ing zinc and diluted sulphuric acid, and at the aperture of 
