For the case of octanol/water partition coefficients, phase I corresponds to the octanol-rich phase and the phase II corresponds to the water-rich phase. The mutual solubility of water in 1-octanol is 0.207 mole fracs, while the mutual solubility of 1-octanol in water is 0.703 × 10 -4 mole fracs . It is therefore reasonable to take the water-rich phase (phase II) to be pure water. On the other hand, the water in the octanol-rich phase (phase I) is not negligible. From eq. 1 this leads to: where the superscript "w" is used to indicate the phase taken to be pure water, and "o*" is used to indicate water-saturated octanol. A positive value of log 10 P o * /w 1 is indicative of a preference of the solute for the octanol-rich phase, while a negative value is indicative of a preference for water. The greater the absolute value, the greater the preference for the respective phase.