QystaNogr.aphy, Capillariiy anif Viscositjn Investigations into capillarity. Lord R u ~ ~ k i & . Phil. i V q . [j]48, 32' (1899). - The first part of the paper i s a study of the weight of drops in their relation to the size of the tube from which they are forming, and it was found by the author that the weight of a drop of any liquid, of which the density and surface-tension are known, can be calculated by the expre4sion Mg =3.S T a, being the radius of the tube and T the capillary tension. Considering the views of Gernez, that the activity of a glass or metal rod to liberate bubbles of gas from supersaturated gaseous solutions is due to a thin filfii of air, it is found that when the activity is destroyed by heating, and the rod enclosed in a hermetically sealed tube for seven years in contact with air, that the activity is not restored. Whereas when exposed to the air of the laboratory for a f e n days, activity is restored. The position maintained by Tonilinson that the activity is clue to a thin film of grease appears to be substantially correct. I n regard to colliding jets the author discusses the causes influencing the condition for rebound or amalgamation of the drops, and studies the behavior in atmospheres of different gases. Air, oxygen and coal gas, were without effect, while carbonic acid, nitrous oxide, sulphurous anhydride, and steam at Once caused union. Hydrogen was found to act in a peculiar manner, sometimes causing union and sonietinies without effect. From experiments on the tension of contaminated water-surfaces and a consideration of molecular magnitudes, it is found that the tension of a thin film of oil on water must be the same as that of pure water. B change in tension must ensue for the oil film spreading out over water and corresponds to the point where repulsive forces resisting contraction cease to act, or to the formation of a complete layer one molecule thick. The diameter of a molecule of oil is found to be about 10-6 mm. N.T. B. Viscosity of solutions. R.Hosting. Phil. Mag. [ j] 49, 274 ( I F ) . - By the method of Thorpe and Rodger ( I &) for the determination of the viscosity of liquids, the author proposes to extend the work to embrace =me typical solutions. -4s a preliminary result, t o find out the limit of accuracy of his appwatus, the viscosity for water for three different temperatures was determined and compared with the results of Poiseuille, Sprung, Slotte, and Thorpe and Rodger. Only two solutions are given in this paper: sodium chloride and sugar. H . T. B.
