Under laboratory conditions a very large fermentative evolution of carbon dioxide takes place in logs during both seasoning and flotation, increasing their gas phase and their buoyancy. The principal changes which take place in the water-gas system of logs during seasoning and flotation have been followed by weight measurements and analyses showing water distribution.End penetration has been shown to be an important factor in sinkage, at any rate when evaporation from the upper surface of the log is considerable. Bolts, 2 ft. 8 in. long gained, during flotation for 8 months, from two to three times as much water when their ends were unpainted as when they were painted. End penetration, combined with evaporation, was found to create through the log a current of water which helps to transport dissolved gases, and to reduce the volume of the gas bubbles held in the cells. It thus acts doubly towards reducing buoyancy by replacing evaporation loss and by facilitating the escape of the imprisoned gases.