physical laws to which the properties of gas mixtures conform (1) The pressure of a mixture of gases that do not chemically interact with each other is equal to the sum of their partial pressures. This law is explained by the molecular-kinetic theory of ideal gases. It is also roughly applicable to real gases at temperatures and pressures far from the critical values. (2) At constant temperature, the solubility of each component of a gas mixture in a given liquid is proportional to its partial pressure over the liquid (that is, each gas dissolves as if it were alone in a given volume). This law is an important supplement to Henry’s law, according to which the solubility of an individual gas is proportional to its pressure. It is applicable to gases whose behavior is close to that of an ideal gas, and only on the condition that the solubility of the gas not be great. Dalton’s laws were discovered in 1801 and 1803 by J. Dalton.