Note on opalescence in fluids near the critical temperature

Abstract

The phenomenon of opalescence at and near the critical temperature has been observed by Travers and Usher under exceptionally favourable conditions, owing to the great width (8 to 10 mm. internal diameter) of the tubes they employed. The opalescence is, however, distinctly visible, and can be studied in much narrower tubes, such as those (0·15 mm. internal diameter) used in my own investigations. The experiments of Travers and Usher were carried out, for the most part, in such a manner that the total volume of the substance investigated remained constant, while the temperature rose very slowly. In my experiments, on the other hand, the substance was kept at its critical temperature, and the volume was altered (usually diminished) by equal stages. The opalescence was always seen, but notes of its position and character were only made with a few substances—isopentane and normal pentane, hexane, and octane.