XIX.—On the expansion of liquids
Journal of the Chemical Society Transactions
THOUGH every liquid has its own peculiar coefficient of expansion, it has long been a desideratum (as may be seen for example from abstracts published in the Fortschritte der Physik since 1845) to find a general expression for the expansion of all liquids. The generalisation which I now lay before the Society is connected with the discussion of this question which has already taken place, and with the additional experimental material which has been collected by chemists, chiefly for the purpose
... fly for the purpose of studying the specific volumes of liquids a t their boiling temperatures. The present paper is, however, limited to the discussion of the physical side of the question of the expailsion of liquids. At some future time I may direct attention to the history of the subject, and to the consideration of the connection between the expansiou of liquids, their composition, and other properties. From all that we know about the expansion of liquids (Pierre, Eopp, Thorpe, Elsasser, and others) we can now easily see that the change of volume V with increase of temperature, t, takes place uniformly and regularly f o r liquids of different composition and properties, but the usual empirical formula V = 1 + At -!-Bt2 + Ct3 + .. .. . . .. . . (1) by which the connection between V and t is represented, does not allow a direct conclusion of this kind to be drawn. To make this clear, the adjoining table has been drawn up containing the data* for the expansion of the 47 liquids studied by Thorpe (Qhem. SOC. J., 1880, Trans., 141, 327) ; they are arranged in the order of increase of expansion, and show distinctly the regularity and quantitative uniformity in the expansion of liquids of the most different natures. * For PBr, and ASP, Thorpe's experimental data were recalculated by me, and in the table are given numbers following from my calculations, whereas for all other bodies numbers are given, following from Thorpe's own int,rrpolation (formula I). According to Thorpe't calculations, the volumes of PBr3 a t 10") 30°, 60") looo, and 150" = 1.0085, 1.0258, 1.0528, 1.0914, and 1.1448. Their accordance with the formula given below (K = 0*000841) is still greater than in the c.ise of numbers recalculated by me. Thorpe's data for PBr, agree very closely with those of Pierre, and this allows the greater confidence to be put in the numbers referring to this liquid.