Dysbarism: osmosis caused by dissolved gas?

The pressure in an osmometer, filled with nitrous oxide-saturated water separated from water by a polyurethane polyether membrane 2.5 microns in thickness, rose slowly by 8 to 20 millimeters (of water) in 10 minutes before gradually returning to close to zero within 2 hours. The permeation coefficient of the membrane was approximately 1000 times greater for water than for gases. The osmotic pressure of water saturated with nitrous oxide at 1 atmosphere, derived from the freezing point of the gas solution, was 1.5 atmospheres. It is concluded that dissolved gases exert osmotic pressure. Partial-pressure gradients of dissolved gases in the tissues of animals and man should cause flows of water along osmotic gradients, which may partially account for some of the symptoms and signs of dysbarism.