The permeability of isolated rat-liver mitochondria to sucrose, sodium chloride and potassium chloride at 0°

hydrogen-bonding in the ions concemed. They concluded that the combination of these effects en- hances the acid strength of the 2-isomer more than that of the 1-isomer. The fact remains that the 2-isomer is the stronger acid above 18-90, and con- sequently it must be assumed that other effects exist which make the 1-isomer the stronger acid below this temperature. The results obtained here serve as a warning of the dangers of using experimental pK values with a possible error of as much as + 0 03 unit as a basis for conclusions about the magnitude and direction of effects such as the statistical effect and the inductive effect. SUMMARY 1. The second dissociation constant of glycerol 1-phosphate has been determined over the range 5-50at 5' intervals, cells without liquid junction with hydrogen and silver-silver chloride electrodes being used.