( 51^3 ) 
from each other , fince that they may un-feparated Aide 
down by the fides of the Glafs ^ to which, it is well known 
and vifiblctotheeye, the Quickfilvcr is not at all apt to 
ftick, but doth rather decline that contaft 5 in like manner 
as wc find Water not apt to Joyn with Oyle or Greafe 5 
though Water to Glafs, and Quickfilver to Gold, do very 
readily apply themfel ve.^. So that there needs no fuch Force 
todil joyn the Quickfilver from the Glafs, whatevcrihere 
may be for dif joyning its parts one from another. 
If therefore wc fliould fuppofe the preflure of the Gr(>jjer 
Air downwards on A 8 (the furface of the ftagoaot Q^iick-" 
filver,) and confequently, by means thereof^ upwards a£ C, 
fufBcient only to bear up that in the Tube to the height of I§ 
but the (uper-added weight or preflure of the Purer Air 
to hold it up as high as D (75 inches or more, ) while it is 
full , and the Quickfilver well cleans'd 5 as if fo long it 
could not enter at D 5 but in cafe it be not (o cleanfed^or be 
already funk 'to H 5 this ^nrer Air would enter at D, and 
Uuuuii ihruft 
