The relationship that defines the partition of a soluble or partially soluble species between the gas and solution phases. It is often represented as Hc. It is the relationship of species dissolving but not reacting in solution to those in equilibrium in the gas phase. The equation used for this is: [Caq] = [Hc]*[Cg ]. Hc is the Henry's Law Constant. This may be regarded as a measure of the molecules in a gas to those dissolve in solution, and this relationship is temperature dependent. Cg and Caq are the concentrations or partial pressure of species C in gas and aqueous solution, respectively. [Environmental Science and Technology; v 28; p 2133; 1994] [Journal of the Tennessee Academy of Science; v 69; p 1; 1994.]