1of the ſurface of that in the Veſſel.
And here, for the Illuſtration of the
foregoing Experiment, it will not be a
miſs to mention ſome other particulars
relating to it.
foregoing Experiment, it will not be a
miſs to mention ſome other particulars
relating to it.
Firſt then, When we endeavor'd to
make the Experiment with the Tube
cloſ'd at one end with Diachylon inſtead
of an Hermetical Seal; we perceiv'd, that
upon the drawing of ſome of the Air out
of the Receiver, the Mercury did indeed
begin to fall, but continu'd afterwards to
ſubſide, though we did not continue pum
ping. Whence it appear'd, that though
the Diachylon that ſtopt the end of the
Tube were ſo thick and ſtrong, that the
external Air could not preſs it in (as expe
rience taught us that it would have done,
if there had been but little of it) yet the
ſubt'ler parts of it were able (though
ſlowly) to inſinuate themſelves through
the very body of the Plaiſter, which it
ſeems was of ſo cloſe a Texture, as that
which we mention'd our ſelves to have
ſucceſsfully made uſe of in the Experi
ment De Vacuo ſome years ago. So that
now we begin to ſuſpect, that perhaps one
Reaſon, why we cannot perfectly pump
out the Air, may be, that when the Veſſel
make the Experiment with the Tube
cloſ'd at one end with Diachylon inſtead
of an Hermetical Seal; we perceiv'd, that
upon the drawing of ſome of the Air out
of the Receiver, the Mercury did indeed
begin to fall, but continu'd afterwards to
ſubſide, though we did not continue pum
ping. Whence it appear'd, that though
the Diachylon that ſtopt the end of the
Tube were ſo thick and ſtrong, that the
external Air could not preſs it in (as expe
rience taught us that it would have done,
if there had been but little of it) yet the
ſubt'ler parts of it were able (though
ſlowly) to inſinuate themſelves through
the very body of the Plaiſter, which it
ſeems was of ſo cloſe a Texture, as that
which we mention'd our ſelves to have
ſucceſsfully made uſe of in the Experi
ment De Vacuo ſome years ago. So that
now we begin to ſuſpect, that perhaps one
Reaſon, why we cannot perfectly pump
out the Air, may be, that when the Veſſel
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