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The apparatus used by Mr. Merton in the above-mentioned paper was very kindly handed over to the author. The following experiments were made with it:—Five grammes of metallic uranium were finely powdered in a steel mortar and then heated to redness in a water-pump vacuum for half an hour. The metal was then transferred to a small bulb in which the metal could be bombarded with the cathode discharge, and this tube sealed on to the Merton apparatus. A small bulb containing charcoal, a hard glass tube containing copper and copper oxide, and a small bulb with phosphorus pentoxide were also sealed on to the apparatus. The whole was then pumped out and washed out several times with oxygen till the spark would not pass in the tube containing the uranium. The tube was then heated as strongly as possible and the gases pumped off and examined; carbon gases and hydrogen were present, but only just enough helium and neon to detect them in the ordinary was using a capillary tube. The tube was again washed out with oxygen and pumped till the spark would not pass through the tube containing the uranium. The palladium tube was then heated for about 20-30 seconds as as to admit hydrogen and allow the spark to pass. The bombardment of the uranium lasted about two hours. During all this time carbon gases and hydrogen were evolved from the metal. These were absorbed by keeping the charcoal bulb cooled in liquid air and heating the copper oxide. At the end of Experiment 1 enough helium and neon at about 2 mm. pressure remained to fill the capillary examining tube and also a small space below. Experiment 2.—Bombardment for one and a-half hours. Rather less helium and neon. (The helium lines–red, yellow, and green–not so strong as in Experiment 1.)

A transient plasma is located within the Fabry-Perot resonator of a dc hydrogen cyanide laser. Plasma tuning sweeps the resonator modes through the emission line of the HCN molecules and produces pulses of far-infrared output radiation. Pulse production by hydrogen, nitrogen, helium, and argon pulsed plasmas is discussed.

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The reaction of He with the epsilon phase of the 50 wt. % U--Zr alloy is studied using a sensitive vacuum microbalance apparatus to prepare the alloys, a sensitive McLeod gage to measure the dissociation pressures, and x-ray diffraction analyses to determine the phases present in the alloy. Although the reaction of H/sub 2/ with the alloy is very rapid at 100 deg C for oxide free surfaces, homogenization is very slow. Hydrogen alloys are prepared in the composition range of U/sub 0.28/Zr/sub 0.72/H/sub 0.0007/to U/sub 0.28/Zr/sub 0. 72/H/sub 0.121/ and the dissociation pressure measurements determined in the temperature range of 300 to 600 deg C. Due to the slow processes of homogenization, the hydride ZrH/sub 1.2/ is not readily precipitated below 400 deg C. On heating to 525 deg C and cooling, the hydride is readily formed for compositions of U/sub 0.28/Zr/sub0.72/H/sub 0.035/ and higher. For lower H/sub 2/ compositions, the hydride is not found in the x-ray diffraction patterns on heating these compositions to 525 deg C and cooling. It is suggested that small hydride nuclei are formed which are not observable by x-ray diffraction methods. Due to a slow rate of metallic diffusion, these nuclei cannot grow.more » The solubility of H/sub 2/ in the alloy is determined to be approximately 0.02 at.% at 500 deg C. This is a smaller value than that found for pure Zr. However, the heat of solution of hydride is +8,900 plus or minus 1,000 calories per gram atom and compares with a value of +8,600 calories per gram atom found for Zr. A transformation of the epsilon to gamma phase of the alloy is found near 550 deg C. (auth)« less