The solubility of air in fats, and its relation to caisson disease

Abstract

As is now well known, the very varied symptoms produced by rapid decompression from high atmospheric pressures, and popularly known as “ caisson disease” or “ diver’s palsy,” are due to liberation of bubbles of gas—chiefly nitrogen—in the blood and tissues. In the course of a recently published investigation, I found that air is much more soluble in certain oils than in water. Dr. J. S. Haldane pointed out to me the interest of this fact in connection with the causation of caisson disease, and at his suggestion I have repeated and extended my observations. The fats experimented with were olive oil, cod liver oil and lard. In the case of the first two, the solubility was measured at 15° and at 37° C., whilst for lard it was determined at 45° C. In the observations made at room temperature, the oil was shaken violently with air in a bottle for several minutes, and was allowed to stand for 1 to 1½ hours till all the air bubbles had risen to the surface. It was then weighed, and about 40 to 50 grammes of it were sucked up into the vacuous flask of a Geissler’s mercury pump. This flask contained 70 to 100 c. c. of 0·5 per cent, sulphuric acid which had previously been well boiled for an hour so as to get rid of all traces of air. The mixture of oil and water was now boiled for half an hour, the oil breaking up into a very fine emulsion and giving up practically all of its gas in the first few minutes. This gas was pumped off and analysed with Haldane’s gas analysis apparatus. The oil was boiled with dilute acid instead of water, so as to obtain the whole of the carbon dioxide present, both combined and in solution. In determining the solubility at 37°, the oil, previously saturated at room temperature, was warmed to about 38° to 39°, and was shaken vigorously with air for about two minutes. At the end of this time its temperature had fallen to about 36°·5. It was warmed up a second time and the shaking repeated, and was then kept in a water bath at 37° for about half an hour in the case of the cod liver oil, and an hour in the case of the olive oil, these being the times required for all the bubbles of air to rise to the surface. The gaseous content of a weighed amount of the oil was then determined as before. The results obtained are given in the tables. They represent the volumes of gas, reduced to 0° and 760 mm., contained in 100 c. c. of the oil at the temperature recbrded, when saturated with air at a pressure of 760 mm. To calculate these values, it was assumed that the specific gravity of olive oil at 15° is 0·917, and at 37°, 0·902. The specific gravity of cod liver oil, compared with that of water at 15°, was found by direct experiment to be 0·928 at 15°, and 0*914 at 37°.