A commercial Van Slyke blood gas apparatus (E. H. Sargent Co.) was modified by the authors.The total pressure of the gas and the solvent vapor in the solution chamber was adjusted to a pressure of one atm. The pressure was maintained at one atm during the solution process. The saturated solution was transferred to a bulb below the lower stopcock of the extraction vessel and sealed off. The gas and solvent vapor were then brought to volume over mercury. See2 for details of the extraction procedure.