XIII.—A Method for Determining the Molecular Weights of Dissolved Substances by Measurement of Lowering of Vapour Pressure

Extract

Although various methods have from time to time been described for determining the molecular weights of dissolved substances by measurement, not of boiling-point elevation, but of the reduction of vapour pressure of a solvent due to the presence of a dissolved substance, none of these methods has come into general use. The method here proposed, operating on this principle, offers the possibility of simply determining the molecular weights of non-volatile solutes in any of the ordinary solvents with an accuracy at least equal to that of the ebullioscopic methods, and in an apparatus at least as easily manageable.