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will attrad other Particles very ftrongly j as appears 
by many Chemical DifTolutions, efpecially by the 
alternate Diffolution and Precipitation of Metals in 
acid Menjlrmms. The Reverend and Learned Dr. 
Hales has proved this many Ways, in his Vegetable 
Statics and Hamafiatics. The Elafticity of Air feems 
to confift vv^holly in the repullive Power of its Par- 
ticles, which do not touch one another while the Air 
is in its elaftic State j and if thofe Particles be brought 
nearer and nearer together, the EfFed of their repul- 
Eve Force will increafe, the Airs Elafticity being 
always proportionable to its Denfity by Compreflion, 
which Property will be prefcrv’d, though comprefs'd 
Air be kept a Year or two; notwithftanding Mr. 
Hauksbee in \m^hy(ico-mechantcal Experiments fays, 
that Air will lofe part of its Spring by being very 
much comprefs’d. But the Air with which he try’d 
it, muft have been fill'd with moift Vapours; and it 
is well known, that the Steam of Liquors will lofe 
its Elafticity, efpecially where its Heat decays. I have 
kept feveral Wind-Guns, ftrongly charg’d, for half a 
Year together, in which the Air had loft none of its 
Elafticity : Others have found the Air as ftrong after 
a Year j and I have been told by a Perfon of Credit, 
that a Wind- Gun having been laid by and forgotten 
for feven Years, when it was found, discharg'd its 
Air as many times, and with as much Force, as it 
ufcd to do. Now, though Air, comprefs'd by any 
external Force, does always increafe in Elafticity, as it 
diminifhcs in Bulk; yet it may, by Fermentation, 
diminifh its Bulk very much, without gaining any 
more Elafticity: For if another Fluid, whofe Parts 
repel one another, but attrad the Parts of Air,, be 
mix’d 
