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In order to judge whether the water contributed 
to the diminution of this mixture of nitrous and 
common air, I made the whole procefs feveral 
times in quickfilver, ufing one third of nitrous, 
and two thirds of common air, as before. In this 
cafe the rednefs continued a very long time, and 
the diminution was not fo great as when the mix- 
tures had been made in water, there remaining one 
feventh more than the original quantity of com- 
mon air. This mixture flood all night upon the 
quickfilver ; and the next morning I obferved that 
it was no farther diminifhed upon the admiflion of 
water to it, nor by pouring it feveral times through 
the water, and letting it fland in water two days. 
Another mixture, which flood about fix hours on 
the quickfilver, was diminifhed a little more upon 
the admiflion of water, but was never lefs than 
the original quantity of common air. In another 
cafe, however, in which the mixture flood but a 
very fhort time in quickfilver, the farther dimi- 
nution, which took place upon the admiflion of 
water, was much more confiderable ; fo that the 
diminution, upon the whole, was very nearly as 
great as if the procefs had been inti rely in water. 
It is evident from thefe experiments, that the di- 
minution is in part owing to the ablbrption by 
the water; but that when the mixture is kept a 
long time, in a fituation in which there is no 
water to abforb any part of it, it acquires a con- 
flitution, by winch it is afterwards incapable of 
being abforbed by water. 
In order to determine whether the fixed part of 
common air was depofited in the diminution of it 
bv 
