Abstract. The separation of uranyl nitrate from aqueous solutions of 0.635 M thorium nitrate, 3 M nitric acid and 3 M calcium nitrate by extraction with organic solvents has been investigated. Solvents which gave good separations were 2-tthyl hexyl acetate, ethyl benzoate, n-butyl either and beta-beta- dichloroethyl ether. In general, higher esters, ethers and alcohols are better for separating uranium from thorium that the lower homologues. Several solvents were tested at lower nitric acid concentrations. Dibutyl cellosolve gave a very good separation when the solution was 0.1 M nitric acid. Of the solvent mixtures studied that of equal parts of n-butyl ether and dibutyl cellosolve gave a good separation.

Compilation of the papers presented at a NACA conference on transonic airplane design, including stability and control and configurations with extreme sweep. From Introduction: "The purpose of this conference was to convey to those involved in the study of the aerodynamic problems of transonic aircraft these recent research results and to provide those attending an opportunity for discussion of the results."

From experience gained by NACA test pilots in flying at high subsonic Mach numbers and from interpretation of the data obtained, some general precautionary rules for test flying near sonic Mach numbers have been formulated. The reasons for these rules are discussed and observations are made with respect to the hazards arising from undesirable stability and control characteristics which have been noted in test flights of various airplanes. This paper, although written primarily for the attention of test pilots, contains general information of interest to those who are concerned with various phases of flight testing near sonic Mach numbers.

From abstract: "Using the method of induced radioactivity, the capture cross section of Pb[^]208 for C neutrons is found to be .00045 ± .00015 x 10[^]-24 cm[^]2. This is definitely lower than the value of .001 x 10[^]-24 reported by Maurer and Ramm."

The gust and draft velocities evaluated from acceleration and airspeed-altitude records taken by NACA instruments installed in P-61c airplanes participating in thunderstorm flights 9, 10, and 11 of July 12, 1946, July 17, 1946, and July 18, 1946, respectively, are presented in references 1 and 2 for previous flights. In accordance with a recent discussion with a member of the U.S. Weather Bureau staff, motion-picture records of the pilots' instrument panels for the present flights were inspected to note variations in the readings of a milliammeter used in conjunction with other equipment to indicate ambient air temperature. The inspection indicated that the instrument read zero throughout all traverses.

"In order to determine the aerodynamic effects of an auxiliary belly fuel tank on the Grumman F8F-1 airplane, a wind-tunnel investigation was made on a 1/5 - scale model of the Grumman XF8F-1 airplane. Pitch and yaw tests were made with the model in the cruising and landing configurations for windmilling and take-off power conditions. Tuft studies and static-pressure measurements were also made to determine the flow characteristics in the region of the fuel tank" (p. 1).