Section XVI.—The Determination of the Specific Gravity of the Crystals of a Soluble Salt by Displacement in its own Mother-Liquor, and the Volumetric Relations between the Crystals and the Mother-Liquor which are Established by the Experiment.

The work on the specific gravity of dilute solutions at 19·5° C. reported in the early part of this memoir was interrupted by the arrival of the great anticyclone or heatwave of the summer of 1904, during which observations at a temperature of 19·5° were quite impossible. Indeed, the temperature of the laboratory, whether by night or day, hardly ever fell below 23° C. or rose above 25° C. It persisted over Northern Europe for nearly six weeks, and produced tropical conditions, which were evidenced alike by the high temperature of the air and by its insignificant diurnal variation.