on the combustion of gaseous mixtures. 79 
and the degree of heat I found could be regulated by the 
thickness of the. wire. The wire, when of the same thickness, 
became more ignited in hydrogene than in mixtures of 
olefiant gas, and more in mixtures of olefiant gas than in those 
of gaseous ,oxide of carbon. 
When the wire was very fine, about the of an inch in 
diameter, its heat increased in very combustible mixtures, so 
as to explode them. The same wire in less combustible mix- 
tures only continued bright red, or dull red, according to the 
nature of the mixture. 
In mixtures not explosive by flame within certain limits, 
these curious phenomena took place whether the air or the 
inflammable gas was in excess. 
The same circumstance occurred with certain inflammable 
vapours. I have tried those of ether, alcohol, oil of turpentine 
and naphtha. There cannot be a better mode of illustrating 
the fact, than by an experiment on the vapour of ether or of 
alcohol, which any person may make in a minute. Let a 
drop of ether be thrown into a cold glass, or a. drop of alcohol 
into a warm one. Let a few coils of wire of platinum of the 
~ or fo of an inch be heated at a hot poker or a candle, and 
let it be brought into the glass ; it will in some part of the 
glass become glowing, almost white hot, and will continue 
so as long as a sufficient quantity of vapour and of air remain 
in the glass. 
When the experiment on the slow combustion of ether is 
made in the dark, a- pale phosphorescent light is' perceived 
above the wire, which of course is most distinct when the wire 
ceases to be ignited. This appearance is connected with the 
formation of a peculiar acrid volatile substance possessed of 
acid properties. 
