Fig. 17.
A A, glass tubes.
B, curved glass tube.
C C, rubber tubes.
D, bibulous paper.
E, water surface.
F, brine surface.
"I have seen you exemplify the statement on a small scale, with water and brine, and can not question but that it is true on a large one," I replied.
"So you admit that the assertion governing the surfaces of liquids is true only when the liquids are connected from beneath. In other words, your thought is one-sided, as science thought often is."
"Yes."
Fig. 18.
E, water surface.
F, brine surface.
"Now as to the beds of salt deep within the earth. You are also mistaken concerning their origin. The water of the ocean that runs through an open channel from the one side may flow into an underground lake, that by means of the contact action (suction) of the overlying and surrounding strata is being continually emptied of its water, but not its salt. Thus by absorption of water the brine of the lake becomes in time saturated, starting crystallization regularly over the floor and sides of the basin. Eventually the entire cavity is filled with salt, and a solid mass of rock salt remains. If, however, before the lake becomes solid, the brine supply is shut off by some natural cause as by salt crystals closing the passage thereto, the underground lake is at last drained of its water, the salt crystallizing over the bottom, and upon the cliffs, leaving great crevices through the saline deposits, as chances to have been the case with the salt formations through which I passed with my guide, and have recently described to you."
"Even now I have my doubts as to the correctness of your explanations, especially concerning the liquid surfaces."
"They are facts, however; liquids capable of being mixed, if connected by porous arches (bibulous paper is convenient for illustrating by experiment) reverse the rule men have accepted to explain the phenomena of liquid equilibrium, for I repeat, the lighter one rushes into that which is heavier, and the surface of the heavier liquid rises. You can try the experiment with alcohol and water, taking precautions to prevent evaporation, or you can vary the experiment with solutions of various salts of different densities; the greater the difference in gravity between the two liquids, the more rapid will be the flow of the lighter one into the heavier, and after equilibrium, the greater will be the contrast in the final height of the resultant liquid surfaces."