Diffusion of mercury vapor at T = 200 deg C and P = 13.3 kPa through air, layers of silicon oxides of grain size from -0.063 + 0.05 to -0.2 + 0.16 mm, and oxides of aluminum and iron of grain size -0.063 + 0.05 mm with porosity 0.442-0.807 is experimentally investigated. The diffusion coefficient for the case of diffusion through air amounts to 25.9 centre dot 10~(-5) m~2/s; the effective diffusion coefficient for the case of diffusion through layers of the oxides that were studied is equal to 5.4 centre dot 10~(-5) - 11.2 centre dot 10~(-5) m~2/s, increasing with increasing porosity and mean pore dimension, calculated on the basis of the mean particles dimensions and mean porosity. With an average pore dimension up to 0.1 mm, laws of Knudsen flow of are observed. Knudsen flow of gas is also noted with high pore dimension if the layer consists of finely dispersed particles.
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