Measurement of Osmotic Concentration in Soil.—Strips of filter paper saturated with a cane-sugar solution of known concentration placed in contact with the soil solution must increase or decrease in weight depending on whether the soil solution has a greater or a lesser concentration than the sugar solution. Strips 4 by 4 cm. are folded once, attached to a small silver or copper wire, and dropped into the sugar solution. They are then taken out, the surplus solution removed with dry filter paper, are then quickly weighed, and hung by a wire in widemouthed bottles which contain the soil samples. The wires may be fastened to the corks with sealing wax and a grain of thymol added to  the soil to prevent the growth of fungi and bacteria. The bottles are then placed in a compartment maintained at a constant temperature (ice box or tireless cooker) for 24 hr., when the paper is weighed again. If necessary, the experiment may be repeated with a sugar solution of another concentration. (Braun-Blanquet 1932:131-2)
BRAUN-BLANQUET, Josias. 1932. Plant sociology: the study of plant communities. (Trans.: George D. Fuller; Henry S. Conard) New York: McGraw-Hill Book Company.