new inflammable Air or Gafs, See. 393 
eighteen times, the ftrength of the exploilon diminifhing 
gradually as in other air guns li K 
In the learned work of Mr. antoni, an Italian gen- 
tleman, I find the fame experiment, the account of which 
is accompanied with a figure of fuch an air gun, in which 
the author fired one ounce of gunpowder, the barrel be- 
ing very flout, and of a fize capable of containing ten 
ounces. He afterwards let a quantity of this compreffed 
air out by a valve in the fame way as it is done in the 
common air guns. This one ounce of gunpowder 
yielded air enough to propel a leaden bullet through a 
hoard three lines thick, at the diftance of forty paces, and 
to repeat the procefs fixteen or eighteen times (e) . 
The difference of the quantity of elaftic fluid obtained 
from the firing of gunpowder by Mr. robins and others 
might be owing to the difficulties attending the invefti- 
gation, or to the different proportion of the ingredients 
ufed in the compofition of the powder; as it is well 
known, that gunpowder for the ufe of the army is 
made of five or fix parts of nitre to one of charcoal, 
. (d) Extrait cPun Journal de Voyage cl’Itali e, par M. de la condamine* 
infere dans les Memojres de PAcademie Royale des Sciences de Paris* 1757* 
P- 405- 
( e) Examen de la Poudre traduit de lltalien de M* antoni* par M. le Vif- 
comte de elavigny* 1773., 
aucl 
