METHODS AND MANIPULATION „ apart symmetrically on the line as shown. By means of a fine glass pipette, drop sufficient of solution (A) on the point A' to form a circular zone about 0-5 cm. in diameter. Wash pipette thoroughly, and then similarly place solution (B) on the point B'. Dry the strip in the air. Now place 35 ml. of the mixed solvent (C) in the clean cylinder E, and suspend the strip, as described above, to the horizontal arm of G (Fig. 25(A)); adjust the position of the strip so that, when the bung is firmly in position, the bottom of the paper-strip is about 5 mm. above the solvent. Place the cylinder for 5-8 hours in a draught-free place, such as a cupboard, where the temperature is reasonably constant. Now lower the paper-strip, which has become saturated with the solvent vapour molecules, so that it dips about 5 mm. into the solvent. Then close the cylinder, and set it aside as before for 12-18 hours, by which time the solvent will have risen about three-quarters of the
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