Penetration of Liquids into Filter Paper Used in Paper Chromatography

The penetration of liquid into a piece of filter paper hung vertically above a liquid is studied theoretically and experimentally. The height of the ascent of the liquid is proportional to the square root of the time at the initial stage of the penetration, but the proportionality does not hold in a wide range of time. The equation which describes this relationship between the height and time has been derived. The values of the parameters in the equation have been determined for acetone, benzene, water, carbon tetrachloride and ethanol. It is concluded that the capillary gap in the filter paper is about 6 μ in the half distance and the length of the gap is about 3 times larger than the length of the filter paper, if the gap is assumed to be two dimensional.