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Experiment IX. 
A phial of river water weighed exactly 82 grains; 
the fame veffel of fea water weighed exaftly 84; the 
difference was two grains, or as 41 to 42. 
Under all thefe experiments, thefe cubes of cork did 
not feem to have gained any meafurable extenfion ; 
yet it is certain the volume of cork, like mcft other 
fubflances, will alter by the imbibition of humidity. 
The affertion which has commonly been advanced, 
that the bodies of men in general are fpecihcally 
lighter than their refpedtive volumes of water, is not 
quite perfectly founded in truth ; accurate experi- 
ments, minutely obferved, will fatisfadtorily evince 
the contrary to be true. Weighing hydrodically 
the human body cannot be fo precifely performed, 
as to permit us to draw any certain inference there- 
from, as evidently 'appears from the imperfedt at- 
tempts which the ingenious Mr. John Robinfon made 
for that purpofe (fee Philofophical Tranfadl. Vol. L. 
Part II. Page 30) ; on peruiing of which, and the 
• author’s ingenuous confeffion of the inaccuracy of 
his experiments, it occurred, that a naore concife 
and eafy method of obtaining a certainty in this par- 
ticular, might perhaps attend the following attempt 
to difcover the fpecific gravity of the human body in 
water. 
Experiment X. 
After having made the foregoing experiments, 
with a view of afcertaining the fpecific buoyancy of 
cork, and alfo the alteration it might undergo from 
being immerfed in river or fea water, we proceeded 
the more important exarnen, to difcover the pre- 
cife quantity of cork neceffary to fuftain a man in the 
water. 
