Onsager heat of transport for water vapour at the surface of glycerol–water mixtures

The effect of a surface temperature gradient on the water vapour pressure over glycerol–water mixtures has been measured for glycerol concentrations in the range from 80% to 94.5% by weight. Graphs of ΔP versus ΔT are linear, for both positive and negative ΔT, at thicknesses of the vapour layer up to at least eight mean free paths. Compound formation, which for sulfuric-acid/water caused the measured heat of transport to decrease markedly at high acid concentrations, has no discernible effect on the measured heat of transport for glycerol–water mixtures.