Knowing S gives the maximum concentration in moles or milligrams/Liter of blood which can be achieved at equilibrium, i.e. it will be the concentration in air (mg/L)  x   S.

Substances with high S values (methanol, ethanol, acetone, ether, etc.) will take a long time to reach equilibrium between inspired air and blood. Substances with low S values (methane, nitrous oxide, etc.) will reach equilibrium between inspired air and blood very quickly. S value can be taken for water at 37^oC but be careful (see above).

iii) Oil/Water Partition Coefficient