6 j6 Col. koy’s Experiments for 
of quickfilver, carefully put into the tube, but not boiled 
therein ? 
With this view, the ftandard barometer and apparatus 
were left out during the night of the 29th, that they 
might acquire the fame temperature, which was found 
next morning to be 34°7; the unboiled quickfilver Hand- 
ing -^oth of an inch higher than that which had been 
boiled. The lamps being applied to the velfel, the 
lengthening of the unboiled column was perceived, on 
the whole, to be more irregular, and the progreffive di- 
minution quicker, than in former experiments ; fo as to 
give, for the maximum of expanfion, only .443 for 1 8o°. 
On the morning of the 31ft, the unboiled column, 
which on the preceding day had been the higheft, was 
lower than the other by near—ths of an inch, the tempe- 
rature of both being 3 i°~. As the water acquired heat 
from the. application of the lamps, the rate of expanfion 
diminifhed; and,. at boiling, was only .405 fori8o°. The 
operation of the 30th feems to point out, in a manner 
fufficiently conclufive, that the air contained in the un- 
boiled quickfilver, rendered its fpecific gravity lefs, than 
that which had been boiled even a great while before ; 
fince it required a longer column of the firft, to counter- 
balance the weight of the atmofphere. And though the 
vacua might poflibly, at the beginning, have been equally 
compleat 
