inserted and the tube lowered further. This forces some pyrogallol into the tube and hastens the reaction. The level of the stopper is marked with gummed paper. When an interval of ten minutes shows no further rise in level of the liquid in the tuhe, the bulb and tube are brought to the same level (C). The level of the liquid is marked with gummed paper and the percentage of oxygen calculated in the usual way. Advantages In the old method, the tuhe which projects through the stopper was filled by opening the pinchcock, allowing the liquid to flow through the tube and then closing the pinchcock. The stopper was then inserted in the test tube. Filling the tube is accomplished more conveniently and without soiling the bands, by the modified method. This method is also more rapid. The use of a bulb with a loose-fitting cork, in place of the open funnel, is an advantage. As the oxygen in the bulb is absorbed, the bulb soon becomes filled with nitrogen (except for the small amount of oxygen admitted by diffusion). The pyrogallol is therefore kept active and the determination is consequently more rapid. It has not been the experience of the writer that a determination can be made "in a few minutes," by either method. More accurate results have in general been obtained by the students using this method. This is probably due to the fact that with the inverted test tube, the occasional leaks occtirring around the glass plug, rubber stopper, etc., are eliminated as a source o f m o r , for the pyrogallol on entering the inverted tuhe "seals" any leaks without changing the volume or the pressure of the enclosed air. With the old method, a slight leak, unnoticed by the student, resulted in a high result due to the escape of air and its replacement by the pyrogallol. Sometimes also, an enor was introduced by the escape of a bubble of air through the vertical tube owing to temperature changes. This is eliminated in the modified method. The leveling bulbs were made by our technician from ordinary soft glass 150 cc. flasks. The use of dropping-funnels is not recommended.
W. D. Harkins, Willard Gibbs Medalist. W. D. Harkins, professor of physical chemistry at the University of Chicago, has been chosen as the recipient of the Willard Gibbs Medal for 1928. The award was made on May 25th at the regular meeting of the Chicago Section. Dr. Harkins is particularly known for his researches on isotopes and a t w i c structure.
