The primary purpose for which the open hydrometer was designed was to investigate the specific gravity and the displacement of solutions having concentrations in the neighbourhood of that of saturation. In § 90 we have seen the satisfactory result of experiments made for this purpose with solutions of chloride of calcium containing 6·3 grm.-mols. CaCl2 per 1000 grams of water. Experiments in the same direction were made with solutions of chloride of calcium of still higher concentration. A parent solution was made, which, on the basis of published data relative to the solubility of the salt, should be supersaturated at 19·5°C. With it, it was intended to produce the solution saturated at this temperature, and to study its specific gravity and that of solutions formed by diluting it with small quantities of water.