Charles's Law.

Charles's law states that the volume of a gas is directly proportional to its temperature. First discovered by French scientist Jacques Charles in 1787, the principle eventually became part of the combined gas laws—alongside Boyle's law and Gay-Lussac's temperature-pressure law—which together describe the behaviors of gases under a variety of conditions. Charles's law is often referred to alternately as Gay-Lussac's law or Charles and Gay-Lussac's law because it was first published by Joseph-Louis Gay-Lussac rather than by Charles himself.