A vacuum is a place that does not contain anything, not even air.
When a vessel contains water and we pour the water out, does that produce a vacuum?
No; because air passes in and fills the vessel.
How then can a vacuum be produced?
A vacuum in any place, can be produced only by drawing the air out of it.
When a vacuum is produced, what does the surrounding air try to do?
It tries to get in so as to fill the vacuum.
With what force does the air try to fill a vacuum?
With a force of fifteen pounds on every square inch of surface.
When a vacuum is produced in contact with a liquid, what does the liquid do?