[243] Since iodine monochloride in the liquid state is only very slightly dissociated, the bend at C is very sharp (see p. [147], footnote). See also the investigation of the system pyridine and methyl iodide (Aten, Versl. Konink. Akad. Wetensch. Amsterdam, 1905, 13. 462).
[244] This upper branch of the curve is not shown in the figure, as the ordinate corresponding to 30° would be very great.
[245] Stortenbeker, Zeitschr. physikal. Chem., 1889, 3. 22.
[246] Ramsay and Young, Journ. Chem. Soc., 1886, 49. 458.
[247] Van't Hoff, Lectures on Physical Chemistry, I. p. 77 (Arnold).
[248] This is different from what we found in the case of non-volatile solutes (p. [126]). In the present case, the partial pressure of the iodine in the vapour will be lowered by addition of chlorine, but the total pressure is increased.
[249] The diminution of volume is supposed to be carried out at constant temperature. The pressure and the composition of the phases must, therefore, remain unchanged, and only the relative amounts of these can undergo alteration.
[250] At point b the ratio of chlorine to iodine in the solution is less than in the monochloride, so that by the separation of this the excess of chlorine yielded by the condensation of the vapour is removed.
[251] Roozeboom, Rec. trav. chim. Pays-Bas, 1884, 3. 29; 1885, 4. 65; Zeitschr. physikal. Chem., 1888, 2. 450.
[252] Two curves "enclose" a field when they form with one another an angle less than two right angles.