Some barometers use long glass tubes filled with mercury inverted in a dish. Air pressing down on the surface of the dish forces the mercury up the tube. Normal air pressure can support a column of mercury about 760 mm high. We use air pressure all the time when we breathe. When our diaphragm moves down, air is pushed into our lungs from the outside, expanding the volume of the chest cavity.
Air is matter, air is there.
Children's Television Workshop. Entertaining science experiments with everyday objects. Conceptual physics, 2d ed. Newton's Apple is a production of KTCA Twin Cities Public Television. Made possible by a grant from 3M. Educational materials developed with the National Science Teachers Association.