in a Flour- Warehouse . 
03 
8aluees suspected. I do not however deny the possibil- 
ity of its having been caused by the meteor which was 
supposed to have been the occasion of it ; for, there is a 
kind of hepatic air continually arising from those ingre- 
dients, when wetted with water, and the least dame is 
sufficient to kindle this aeriform vapour. 
It is very evident, from the facts which I have related, 
that spontaneous inflammations being very frequent, and 
their causes very various, too much attention and vigi- 
lance cannot be used to prevent their dreadful effects. 
And consequently it is impossible to be too careful in 
watching over public magazines and storehouses, parti- 
ticularly those belonging to the ordnance, or those in 
which are kept hemp, cordage, lamp-black, pitch, tar, 
oiled cloths, &c. which substances ought never to be left 
heaped up, particularly if they have any moisture in 
them. In order to prevent any accident from them, it 
would be proper to examine them often, to take notice if 
any heat is to be observed in them, and, in that case, to 
apply a remedy immediately. These examinations 
should be made by day, it not being advisable to carry 
a light into the magazines, for, when the fermentation is 
sufficiently advanced, the vapours which are disengaged 
by it, are in an inflammable state, and the approach of a 
light might, by their means, set fire to the substances 
whence they proceed. 
Substances in fermentation are very often unable to 
inflame of themselves, but the simple contact of flame is 
sufficient to kindle them rapidly, as many examples de- 
monstrate ; so that we might make a separate class of 
those substances in which inflammation cannot take place 
of itself, but which are set on fire by the approach of 
flame ; of this we have an example in the accident which 
happened in the flour-warehouse. 
Ignorance of the fore-mentioned circumstances, and a 
