8a Sir H. Davy’s experiments and observations 
small quantities of air were admitted, its heat speedily in- 
creased; and by regulating the admission of coal gas and 
air it again became white hot, and soon after lighted the flame 
in the cylinder, which as usual, by the addition of more at- 
mospherical air, re-kindled the flame of the wick. 
This experiment has been very often repeated, and always 
with the same results. When the wire for the support of 
the cage, whether of platinum, silver, or copper, was very 
thick, it retained sufficient heat to enable the fine platinum 
wire to re-kindle in a proper mixture a half a minute after 
its light had been entirely destroyed by an atmosphere of 
pure coal gas ; and by increasing its thickness the period 
might be made still longer. 
The phenomenon of the ignition of the platinum takes 
place feebly in a mixture consisting of two of air and one of 
coal gas, and brilliantly in a mixture consisting of three of 
air and one of coal gas : the greater the quantity of heat pro- 
duced the greater may be the quantity of the coal gas, so that 
a large tissue of wire will burn in a more inflammable mix- 
ture than single filaments, and a wire made white hot will 
burn in a more inflammable mixture than one made red hot* 
If a mixture of three parts of air and one of fire damp be intro- 
duced into a bottle, and inflamed at its point of contact with 
the atmosphere, it will not explode, but will burn like a pure 
inflammable substance. If a fine wire of platinum coiled at 
its end be slowly passed through the flame, it will continue 
ignited in the body of the mixture, and the same gaseous 
matter will be found to be inflammable and to support com- 
bustion. 
There is every reason to hope that the same phenomena 
