I. Researches upon the specific volumes of liquids

The results of the observations made by Pierre and Kopp upon the boiling-points, specific gravities, and thermal expansibilities of the trichlorides and tribromides of phosphorus, arsenic, and antimony have led Kopp to suppose that the specific volumes of phosphorus, arsenic, and antimony, in their liquid combinations, may be identical. The same conclusion has been drawn with respect to tin, titanium, and silicon from Pierre’s observations upon the tetrachlorides of these elements. The common value of P, As, and Sb would appear to be about 27; that of Si, Ti, and Sn about 35. But on examining the details of the observations, it becomes evident that this conclusion is not strictly borne out bi the results; the numbers obtained for the individual members of the group differ in many cases considerably from the common value, the divergences being far wider than could arise from errors of observation either in the determination of the physical constants or in the estimation of the atomic weights of the constituent bodies. In fact the order oi the divergences would seem to render it probable that the specific volumes of the several members of a family of elements increase with their atomic weights.