6 JS Account of an Explosion 
Dung also, under certain circumstances, inflames spon- 
taneously. 
We have likewise examples of spontaneous inflamma- 
tions in the productions of the animal kingdom. Pieces 
of woollen cloth, which had not been scoured, took fire 
in a warehouse. The same thing happened to some 
heaps of woollen yarn ; and some pieces of cloth took 
fire in the road as they were going to the fuller. These 
inflammations always take place when the matters heap- 
ed up preserve a certain degree of humidity, which is 
necessary to excite a fermentation; the heat resulting 
from which, by drying the oil, leads them insensibly to a 
state of ignition ; and the quality of the oil, being more 
or less desiccative, very much contributes thereto. 
The mineral kingdom also often affords instances of 
spontaneous inflammation. Pyrites heaped up, if wetted 
and exposed to the air, take fire. Pit-coal also, laid in 
heaps, under certain circumstances, inflames spontane- 
ously. M. Buhamel has described two inflammations of 
this nature, which happened in the magazines of Brest, in 
the years 1741 and 1757 .* 
Boats loaded with quick lime have taken fire as they 
sailed along ; and lime, by being wetted, has often set 
fire to substances which happened to be near it. 
Cuttings of iron, which had been left in water, and 
were afterwards exposed to the open air, gave sparks, 
and set fire to the neighbouring bodies. For this obser- 
vation we are obliged to M. de Charpentier. 
The explosion of a powder mill, which happened in 
the year 1784, in the royal manufactory of Turin, the 
cause of which could not be discovered, may perhaps 
have been occasioned by the spontaneous inflammation of 
the ingredients of which gunpowder is made, as Count de 
Memoires de FAeademie 
