<P> The gas laws were developed at the end of the 18th century, when scientists began to realize that relationships between pressure, volume and temperature of a sample of gas could be obtained which would hold to approximation for all gases . Gases behave in a similar way over a wide variety of conditions because they all have molecules which are widely spaced, and the equation of state for an ideal gas is derived from kinetic theory . The earlier gas laws are now considered as special cases of the ideal gas equation, with one or more variables held constant . </P> <P> In 1662 Robert Boyle studied the relationship between volume and pressure of a gas at constant temperature . He observed that volume of a given mass of a gas is inversely proportional to its pressure provided the temperature remains constant . 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, with a fixed number of molecules inside, is reduced in volume, more molecules will strike a given area of the sides of the container per unit time, causing a greater pressure . </P> <P> A statement of Boyle's law is as follows: </P>

The volume of a gas is inversely proportional to the pressure of a gas is known as