With a pump. There are a number of different kinds, but all have the property that an intake chamber is caused to enlarge, then shut off with a valve, and the chamber is then compressed and the gas in it vented to the atmosphere. For high vacuums, a metal strip may be evaporated, and the metal vapor tends to trap gas molecules. A laboratory vacuum pump can be had from supply houses for a few hundred dollars.
This message was modified Mar 15, 2016 by a moderator
