Page:Proceedings of the Royal Society of London Vol 69.djvu/495

Rh factory. An equally good agreement was also shown in the other cases which I investigated. From the considerable number of cases I have studied, it would appear that the above method can l>e applied to the calculation of solubilities with close approximation to the truth. As to the range of temperatures or solubilities over which the relationship holds good, no definite statement can be made as yet. In almost all cases the relationship was tested over the whole range of available data ; that is to say, over the range of tempera- tures within which the two substances under comparison have equal solubilities. Several of the deviations are no doubt due to inaccuracies in the determination of the solubilities, and to errors in the drawing of the curves or reading from them.

II. Calculation of Equilibrium Constants. The formula of Ramsay and Young, further, can be applied not only, as has already been shown, to the calculation of vapour pressures and of solubilities, but it can also be used for the purpose of calculating the equilibrium constants of chemical reactions. In this case, R and R' denote the ratios of the absolute temperatures at which the values of the equili- brium constant of the two reactions arc equal. In this case, also, if we know the temperature curve of the equilibrium constant of one reaction, it will be possible to calculate the temperature curve of the equilibrium constant of another reaction, by determin- ing the value of that constant at t\vo temperatures. This is shown by the figures given in Table VI. The two reactions which were compared were those represented by the equations 2111^11... + I..,* and 2CH 3. CO. CH 3 ^CH ;! . CO. CHo. C(CH 3 ),.OH,t two reactions, therefore, which are of a most dissimilar character. As the values of the equilibrium constant of these two reactions were not determined at a sufficient number of suitable temperatures for the present pur- pose, it was necessary to calculate the values of the constant at other temperatures. In the case of hydriodic acid, the constant was calculated for the temperatures 520, 530\ 540, 550, 560, by means of the formula given by Bodenstein :|

log e K = ^1 8 - 1-5959 log, T + 0-0055454T + 2 -6981.

The values found were :

t 520 530 3 540' 550' 560'

K 0-02063 0-02658 0-02759 0-02864 0-02974

In the case of the condensation of acetone to diacetone alcohol, in which case the equilibrium constant was determined at only two

t Koelichen, ' Zeitschr. Phvsik. Chem.,' 1900, vol. 33, p. 129. T Loc. cit.
 * Bodenstein, 'Zeitschr. Pliysik. Chein.,' 1899, vol. 29, p. 293.