Gas laws 1662 Robert Boyle studied the relationship between volume and pressure of a gas of fixed amount at constant temperature. He observed that volume of a given mass of a gas is inversely proportional to its pressure at a constant temperature. Boyle's law, published in 1662, states that, at constant temperature, the product of the pressure and volume of a given mass of an ideal gas in a closed system is always constant. It can be verified experimentally using a pressure gauge and a variable volume container. It can also be derived from the kinetic theory of gases: if a container,
Standard cubic foot of the label "standard", there is a variety of definitions, mainly depending on the type of gas. Since, for a given volume, the quantity is proportional to the pressure and (absolute) temperature, each definition fixes base values for pressure and temperature. The ideal gas law allows then to compute the quantity per unit of volume for actual pressures and temperatures. Since natural gas is an imprecise mix of various molecular species, chiefly methane but with varying proportions of other gases, a standard cubic foot of natural gas does not represent a precise unit of mass, but only a molecular quantity,