Abstract
UNDER this title I have communicated to the Chemical Society the results of a prolonged investigation on the connection existing between the weights of unit volumes of liquid substances and their relative molecular weights (see Journal of the Chemical Society for March, April, May, and June, 1880), and in obedience to a request from the Editor of NATURE I will briefly indicate the scope of the inquiry, and point out the main conclusions to which I have been led. The inquiry, I may say in the outset, has resolved itself into a critical and experimental examination of what are known as Kopp's laws of specific volume. That some definite connection between molecular weight and specific gravity would be traced had been surmised more than forty years since, but all our exact knowledge on the subject is contained in the series of classical memoirs which we owe to Hermann Kopp. Kopp first clearly recognised the necessity of comparing the liquids when under strictly analogous conditions. By dividing the specific gravity of a liquid taken at the temperature at which its vapour-tension is equal to the standard atmospheric pressure—that is, at its ordinary boiling-point—into its molecular weight, we obtain its specific volume. If the specific gravity be referred to the point of maximum density of water, this value represents the number of cubic centimetres occupied by the relative molecular weight of the liquid expressed in grams at its boiling-point under the standard pressure. The numbers thus obtained were first shown by Kopp to exhibit certain definite relations which may be briefly stated as follows:—
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THORPE, T. On the Relation Between the Molecular Weights of Substances and their Specific Gravities when in the Liquid State . Nature 22, 262–263 (1880). https://doi.org/10.1038/022262a0
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DOI: https://doi.org/10.1038/022262a0