A piece of hemlock wood measuring 15.15 x 14.8 x 0.75 cm is to be dried from the two large faces from an initial total moisture content of 90% to a final average total moisture content of lo%, with drying taking place in the falling-rate period with liquid-diffusion controlling. The moisture diffusivity has been experimentally determined as 1.7 x 10^–6 cm²/s. Estimate the drying time if bone-dry air is used. All moisture contents are on a dry basis.