an experiment demonstrating the slow miscibility of two liquids of

VOL. 6, No. 3

EXPERIMENT DEMONSTRATING SLOWMISCIBILITY

523

AN EXPERIMENT DEMONSTRATING THE SLOW MISCIBILITY OF TWO LIQUIDS OF DIFFERENT DENSITIES The experiment outlined below was devised to illustrate the small degree of mixing which occurs when two readily miscible liquids of d i e r e n t densities are permitted to come in contact with each other. The experiment was originally designed to illustrate the flow of sea water into fresh water systems1 and to show the relatively small degree of mixing resulting from such a disturbance. The author has noted that the experiment has been of considerable interest to freshman chemistry students. He has also used it in his introductory lectures on volumetric analysis to impress the student with the necessity for thorough shaking in the preparation of standard solutions. The experiment is best performed with Meyer bulbs as shown in the accompanying figure. The apparatus is completely filled with fresh water up

to the point A. B is a piece of glass tubing connected to the Meyer bulbs by means of rubber tubing. The apparatus is clamped in a horizontal position and about 70 ml. of solution of a salt, acid, base, or sea water added to C. The solution is colored with a suitable indicator before it is introduced into C. Because of its greater density the solution tends to settle to the bottom, and flows into the first bulb of the series, gradually filling the lower portion of the bulb. The displaced water tends to flow upward into C. As soon as the lower part of the first bulb has been filled with the more dense liquid, flow into the bottom of the second bulb will commence. This process will continue until the lower portion of all of the bulbs has been filled with the colored solution, the upper part, containing the less dense solution, remaining colorless. When this has occurred i t will be noticed that the water has displaced considerable of the colored, more dense solution formerly in C, thus showing that it was possible for the water to work its way through the more dense solution in the tube connecting C and the bulbs, with only a small degree of mixing.

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Smith and Thompson, Ind. Eng. Chem., 17, 1084 (1925); Bull.41, Univ. Wash. Eng. Exptl. Sta. (1927).