The Vapor Pressure of Dog's Blood at Body

An evaluation of the colligative properties of the blood is of paramount theoretical importance, for such properties enter as fundamental factors in all physicochemical considerations based either on the kinetic theory or on thermodynamics. Despite this importance, no direct measurements of the colligative properties of blood have been made at body temperature. 1 Our knowledge of these functions is based almost exclusively on freezing point determinations made at 0 °. However, the importance of the colloidal constituents of the blood and the magnitude of the unknown change which temperature may produce in their properties renders the application of such measurements to conditions obtaining in the intact organism rather hazardous. Because of the lack of a direct determination of any of the colligntive properties of blood at body temperature, it was deemed worth while to make such a measurement. To obtain a value for the colligative properties of a solution four possible methods are principally used, viz. the determination of the raising of the boiling point, the lowering of the freezing point, the osmotic pressure, and the vapor pressure. The first of these methods is impossible in the case of blood solutions. Objections to applying freezing point data to blood at body temperature have already been