Analyfts of the Air. 277 
quently thofe fubftances fhould take fire, 
and burn for a fliort time at leaft, which yet 
they did not. 
And that the air's elafticity conduces much 
to the intenfe burning of Fires, feems evident 
from hence 5 that Spirit ci Nitre (which 
by Experiment 75 has but little elaftick air 
in it) when poured upon live Coals^ ex- 
tinguifhes inftead of invigorating them : 
But Spirit of when by being mixt with 
Sal Tartar it is reduced to Nitre, will then 
flame, when thrown into the Fire, viz, be- 
caufe Sal Tartar abounds with elaftick aereal 
particles, as appears by Experiment 74, where 
224 times its bulk of air arofe from a quan- 
tity of Sal Tartar. And for the fame reafon 
it is that common Nitre, when thrown into 
the Fire, flames, tho' its Spirit will not, viz. 
becaufe there is much elaftick air in it, as 
appears from Experiment 72, as well as from 
the great quantity of it, generated in the 
firing of Gun-powder. 
The reafon why Sal Tartar, when thrown 
on live Coals, does not detonize and flame 
like Nitre, (notwithftanding by Experiment 
74 plenty of elaftick particles did arife from 
it) is this> viz. becaufe by the fame Experi- 
T 3 nient, 
