Vapour Pressures.—The submerged bulblet apparatus described in a preceding paper may readily be adapted to determining vapour pressures. The apparatus is unchanged, excepting that the lower part of the thermometer is enclosed in a test-tube containing a portion of the bath-liquid (fig. 1). The interior of the test-tube communicates, through the L-tube, with a gauge, with a pump, and with the atmosphere. The bath is brought to constancy at the required temperature with the pressure in the apparatus above the vapour pressure of the substance. The pressure is next lowered gradually until a continuous stream of bubbles issues from the capillary. Then the pressure is allowed to rise until the stream ceases. The details of manipulation and correction may be understood from the former paper without special description.