Boyle’s law

At a constant temperature, the pressure of a fixed mass of a gas is inversely proportional to its volume: i.e.
pV = K

where K is a constant. The value of K depends on the temperature and on the nature of the gas. The law holds strictly only for ideal gases. Real gases follow Boyle’s law at low pressures and high temperatures.
The law is named for the British chemist and physicist Robert Boyle (1627–91). See gas laws.