This section presents the limited amount of information, some of it still unpublished, regarding solubility and vapor pressure in aqueous solutions at temperatures above 100°C. No attempt is made to cover the wealth of data which exists for temperatures below 100°C., and which is exhaustively tabulated in other places (Int. Crit. Tables, Vol. IV; Handbook of Chemistry and Physics, Chemical Rubber Publishing Co.).

Solubility determinations from the cryohydric point to the triple point of the salt have been carried out for sodium and potassium nitrates (m.p. 308°C. and 334°C., resp.) and for boric oxide (m.p. 450°C.), but for higher-melting salts only parts of certain binary systems with water as one component have been investigated. The experimental methods, in order of decreasing accuracy, are:

(1) Heating water and excess salt in a closed thermostated system, with some device for sampling a portion of the saturated solution for analysis [2, 3];

(2) Heating known weights of salt and water in a closed glass system, and observing the temperature at which the last portion of salt passes into solution [4, 5];

(3) For glass-forming solutes, quenching charges of glass after treatment with excess water in a closed bomb [6, 10];

(4) Observing the discontinuity of . . .