The purpose of this survey was 1) to measure accurately ozone concentration in commercial jet aircraft cabins and/or flight crew compartments on flights above 25,000 ft in order to obtain a 12-month statistical evaluation with emphasis on seasonal and meteorological correlations, and 2) to locate and chart the ozone-enriched air masses in order to obtain further meteorological correlations and to establish any abnormal conditions that result in exposure to large ozone concentrations. The ozone concentration in aircraft was measured during 285 commercial jet flights between September 1, 1962 and August 31, 1963. These flights ranged over all segments of the United States and included sections of Canada and the North Atlantic. All types of commercial jet aircraft currently employed by air carriers were monitored. The ozone measurements recorded on each flight were evaluated, and the data were correlated graphically to show seasonal variations. The maximum continuous ozone exposure encountered on a domestic flight was 20 or more parts per hundred million (pphm) by volume for 140 min; the maximum on a northern flight was between 20 and 30 pphm for 4 hr; the highest concentration encountered was 35 to 40 pphm for 20 min.

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Notes 457 which is close to the value reported in the gas phase,6 2.010. The measured N14 and F19 couplings are 16 and 56 gauss, respectively. ExperimentalThe sieves used in these experiments were Linde6 Molecular Sieves in powdered form. They were heated to 300°and then evacuated at 10~6 atm. prior to the introduction of N2F4 vá 2NF2.The e.p.r. spectra reported herein were obtained with a Varían V-4502 e.p.r. spectrometer system employing 100-kc./sec. modulation and detection. The n.m.r. spectra reported were obtained with a Varían Associates V4300 40-Mc./sec. spectrometer. The sample cells were 5-mm. o.d. and 7 in. long capped by side arms and a Fischer-Porter7 pressure valve for loading the cells with gas.Caution.-N2F4 reacts with Linde Molecular Sieve 10X at room temperature and pressures greater than 0.5 atm. Occasionally we have had samples explode with both 10X and 13X sieves. It is our belief, however, that by vigorous outgassing at 300°and by vigorous exclusion of air these systems may be handled safely.Acknowledgments.-This work was carried out under Contract No. DA-01-021 ORD-11878 (Z) Mod. No. 7. (5) L.

The density of liquid ozone has been measured over the range 77.4 to 174.2°K by means of ozone thermometers. The construction of the thermometers and the operating techniques are described. An equation which relates the specific volume of liquid ozone to the absolute temperature is presented. The equation, V=0.551+(6.25×10—4)T+(3.35×10—6)T2, represents the experimental data to within 0.2%. A density of 1.354±0.001 g/ml is reported for liquid ozone at its normal boiling point, 161°K.