Vapour pressure of water can be use in many experiments, particularly experiments relating to gases. A common classroom experiment in which the vapour pressure at various temperatures table is used is when trying to find the molar mass of butane. The experiment is done by releasing butane gas from a cigarette lighter underwater into glass tubing. By calculating the partial pressure of the gas and subtracting the atmospheric pressure on the day that the experiment was conducted, it is possible to obtain an accurate result. This can be done with other gases with the same process.