822 Spontaneous Ignition of Charcoal 
on the surface of the sifted charcoal, was of the nature 
of inflammable gas, which is equally unextinguishable.* 
The moisture of the atmosphere, of which fresh made 
charcoal is very greedy, appears to me to have concur- 
red in the developement of the inflammable gas, and the 
combustion of the charcoal. 
It has been observed, that charcoal powdered and laid 
in large heaps heats strongly. 
Alder charcoal has been seen to take fire in the ware- 
houses, in which it has been stored. 
About thirty years ago I saw the roof of one of the 
low wings of the Mint set on fire by the spontaneous 
combustion of a large quantity of charcoal, that had 
been laid in the garrets. 
Mr. Malet, commissary of gunpowder at Pontailler, 
near Dijon, has seen charcoal take fire under the pestle. 
He also found, that when pieces of saltpetre and brim- 
stone were put into the charcoal mortar, the explosion 
took place between the fifth and sixth strokes of the pes- 
tle. The weight of the pestles is 80 pounds each, half 
of this belonging to the box of rounded bell metal, in 
which they terminate. The pestles are raised only one 
foot, and make strokes in a minute. 
In consequence of the precaution now taken, to pound 
the charcoal, brimstone, and saltpetre separately, no ex- 
plosions take place ; and time is gained in the fabrica- 
* [Messrs. Aikins must, I presume, advert to the above fact, in the following- 
quotation from their Chemical Dictionary, voL 1. p. 238. although their reference 
is made to No. 36 of the An. de Cliimie. Ed.] 
“ The affinity, of charcoal for oxygen is so considerable, that instances have 
been known of its undergoing spontaneous combustion by simple contact with 
the air. An occurrence of this kind took place at the powder mills of Essonne in 
France. (An. de Chim. 36. p. 93.) A large quantity of recently burnt charcoal had 
been ground in the usual manner, and was deposited in a large receptacle for fu- 
ture use ; some days after, the door of the magazine being opened in order to 
remove a part of the charcoal, an extraordinary heat was perceived, and imme- 
diately a train of fire was observed spreading over the surface of the charcoal, 
and which was not extinguished without much difficulty/* 
! 
