On the osmotic pressures of aqueous solutions of calcium ferrocyanide. Part I. Concentrated solutions

Abstract

In the following communication the experiments on the direct measurement of the osmotic pressures, on the vapour pressures, and on the densities have been carried out in conjunction with Mr. E. G. J. Hartley,those on the compressibilities with Dr. C. V. Burton. In the ‘ Proceedings of the Royal Society,’ Series A, vol. 77 (1906), pp. 156-169,Mr.Hartley and I gave a preliminary account of the determination of the osmotic pressures of strong aqueous solutions of cane sugar by means of measurements of the relative lowering of their vapour pressures as compared to that of water. We deduced a formula for the connection between the vapour and osmotic pressures of a solution, which, in view of the experimental errors, justified the neglect of corrections due to the compression of the solution and of the solvent. Since then Prof. A. W. Porter (‘ Proc. Roy. Soc.,’ A, vol. 79, 1907) has put forward an exact equation in which the influence of these two factors can be taken into account; increased experience with, and further modifications of, the vapour-pressure apparatus apparently justified the belief that the experiments would be more accurate, and therefore it seemed advisable to end endeavour to obtain complete data for the aqueous solutions of some one substance, so as to test the practical applicability of the new formula in its entirety.