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T THE Detroit meeting of the American Chemical Society, April, 1943, an American source of rhenium was announced. A. D. Melaven (Chemical Warfare Service) and J. A. Bacon (University of Tennessee) have extracted potassium perrhenate, KReOt, from flue dusts obtained in roasting molybdenite. The dusts contain in excess of one per cent rhenium. Since the supply from Germany was cut off, rhenium compounds have disappeared from the American market. Sufficient material is now available to warrant small-scale production. J. W. Vagt and L. J. Wood CSt. Louis University) have demonstrated that when (a) esCI and KBr and (b) CsBr and KCl are heated below the fusion temperature, equilibrium is reached according to the reaction: esCl + KBr ~ CsBr + KCL The compounds were identified in the equilibrium mixtures by means of x-ray analysis. F. R. Dunkerley and H. Seltz (Carnegie Institute of Technology) have prepared pure crystalline WC, TiC, and WTiC 2 by dissolving the constituents in either molten aluminum or molten nickel at 2000°C. WTiC 2 , thus formed, consists of beautiful metallic crystals with extreme hardness. In the December 26, 1942 issue of Nature,l Walter Minder of the Radium Institute and Alice Leigh-Smith of the Rontgen Institute, Berne, Switzerland, add support to Minder's previous claim to the discovery of element 85. Thorium emanation ejects an alpha particle to form Thorium A, atoms of which seem to disintegrate in two ways-the majority emit alpha particles but a sma1l'perccntage evidently emit beta particles. The product of the beta ray process is an atom of element 85, which is also beta ray active and is converted to an isotope of radon. Minder's claim to the discovery of element 85 has been disputed by Hulubei and Canchois 2 who claim to have discovered it earlier among the products of disintegration of radon. The earlier claims were reviewed in this column in 1940. 3 R. B. Barnes and D. J. SaUey, of the American Cyanamid Company, recently published 4 a method of determining the
Nature, 150, 767 (1942). Comp!. rend., 210, 696-7 (1940). 3 THIS JOURNAL, 17,498 (1940). 4 Ind. Eng. Chem., Anal. Ed., 15,4 (1943). 1
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quantity of potash in a fertilizer which depends upon the measure· ment of the beta ray activity of the natural radioactive isotope 1~K. The radiation is weak but is measurable by extremely sensitive modern physical instruments. The sample is dissolved and introduced into a special glass cell which surrounds a Geiger-Muller counter. The determination takes a relatively short time compared to the llsuallaborious methods. L. S. F. An invisible "raincoat" which can be formed on cloth, paper, and many other materials by exposing them to chemical vapors from a new compound, thereby making them water repellent, has been developed in General Electric's Research Laboratory at Schenectady, N. Y., by Dr. Winton 1. Patnode who is studying many possible uses of this new method of waterproofing. Called Dri-Film by the G. E. Electronics Department which will market the new compound, one of its most important uses so far is the treatment of ceramic insulators for radio equipment being made for the armed forces of the United States. It is about nine times more effective than the wax used at present as a water repellent, and its results are permanent. Dri-Film is a clear liquid composed of various chemicals which vaporize at a temperature below 100°C. Articles to be treated are exposed, in a closed cabinet, to the vapors for a few minutes. Then they are taken out and, if necessary, are exposed to ammonia vapor. This is to neutralize corrosive acids which may collect during treatment. This "raincoat" is so thin that its structure cannot be determined by chemical analysis. It cannot be seen under a highpowered microscope. But, whatever its nature, it prevents water from spreading to form a continuous film. If moisture does collect, it is in the form of small isolated drops. Another use for the new compound is a laboratory one. The surface of water in laboratory glassware, such as measuring cylinders and hydrometers, is ordinarily curved, low in the center, because the liquid wets the walls and tries to climb them. Such a curved surface, or "meniscus," is prevented if the inside of the container is treated with the water-proofingvapors from Dri-Fihu. Then the water surface is flat and its. height may be read more easily.
A Metho,d for Producing Electrolytic Gas Al\'lASA F. WILLISTON, B. M. C. Durfee High School, Fall River, Massachusetts
IN DEMONSTRATING the very explosive char- bend, To the glass tube attach a piece of rubber acter of electrolytic or detonating gas, the mixture of tubing just long enough to reach the bench on which hydrogen and oxygen produced by electrolysis of a the bottle rests. In a 3-inch mortar to a depth of water solution of sulfuric acid, the gas is often collected about 1 em., place a soap solution. in a very thin glass flask and exploded by an electric Fill the bottle with a solution of sodium hydroxide spark. This requires considerable care, some protec- to within about 1 em. of the center neck, so as to reduce tion against flying glass, and is bothersome. Another the volume of air above the solution to a mil1imum~ method of collection is to pass the gas into a soap solu- Place the tube tightly in the center opening and turn tion and ignite the pubbles of gas with a match. There on the current. Allow enough time for the gas prois often trouble in this case because traces of acid de- duced to displace the air in the tube and bottle, then. stroy the soap bubbles, unless the gas is carefully rest the end of the rubber tube on the bottom of the washed with water and sodium hydroxide solution. mortar beneath the soap solution. In a short time, A very simple method of avoiding trouble and com- about 1 to 2 min. with the current delivered from a 5plicated apparatus is the following: use a 3-neck volt rectifie.r, the mortar will be two-thirds filled with Woulfe's bottle of suitable size, 200 to 500 ml. In the small bubbles of electrolytic gas. two outside openings put the two electrodes from a Shut off the current, set the generator aside, and source of direct current, making sure that the stopper remove the center stopper as an additional safety carrying each electrode fits gas-tight. In the center measure. The bubbles may be easily ignited with a opening place a stopper carrying a short right-angle match held in a pair of crucible tongs. 210
