2-methyl-8-quinolinolato groups are similar to those found in the oxovanadium complex and in the aluminum(III) complex (J).The equation of the least-squares plane, with respect to the crystallographic axes, through the 2-methyl-8-quinolinolato group defined by the atoms N(l), C(l), . . . C(11), 0(12) is: 0.215* + 0.677T -0.728Z = -4.162 (Plane 2) and through the 2-methyl-8-quinolinolato group defined by the atoms N(21), C(22), . . . C(31), 0(32)is:-0.495* + 0.030Y + 0.999Z = 6.242where *, Y, and Z are in Á. The distances from the atoms in each of these groups to their respective planes are given in Table VIII. The carbon atom of the methyl group, C(ll), shows the maximum deviation (0.063 A) from Plane 2, and a ring carbon atom, C( 24), shows the maximum deviation (0.028 Á) from Plane 3. The gallium atom which is not included in the calculation of the least-squares planes lies 0.099 Á above Plane 3 and 0.133 Á below Plane 2. Although the coordinated 2-methyl-8-quinolinolato groups are approximately planar, there is considerably more distortion in this structure than in the oxovanadium(IV) structure. A comparison of the dihedral angles between the two intramolecular planes of the 2-methyl-8-quinolinolato groups reveals an important difference in the two structures. In the oxovanadium(IV) complex, the dihedral angle is 44°1', whereas in the gallium complex it is 69°45'. The distance between the 2-methyl-8-quinolinolato planes that are related by the center of symmetry (V4, lU, V4), is 3.55 A. The 2-methyl-8quinolinolato planes which are packed in a direction almost perpendicular to the c-axis are 3.89 Á apart when related by a center of symmetry, and 3.99 Á apart when related by a twofold axis (Figure 7). Intermolecular contacts that are less than 3.5 Á are shown in Figure 8.

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Counting Properties of Toluene Triton Water Mixtures. Because the greatest difficulties are found in the counting of weak / 3 emitters, tritium has been used to evaluate the various mixtures. As shown in Table I, addition of the several Triton surfactants t o toluene solutions of scintillator in the absence of water has relatively small effects on the counting efficiency of tritium. Mixtures of Triton and scintillation solution are useful for solubilizing small amounts of biological material for counting (5). For example, we have used these mixtures to count E. coli cells precipitated with trichloroacetic acid. Tables I1 and I11 show the counting efficiencies of tritiated water in suitable mixtures of Triton, scintillation solution, and water in the cold and at room temperatures, respectively. The differences in counting efficiencies between the two sets of conditions may be caused by a variety of factors such as differences in instrumentation and differences in light yield from the phosphors at the different temperatures. Within each group, however, the counting efficiencies of the solubilized samples are similar to those of the emulsions even though many of the emulsions are quite murky. The temperature range over which the mixtures form homogeneous solutions can be adjusted to any desired value by the use of appropriate mixtures of Triton surfactants as illustrated by the mixtures of Triton X-45 and X-114 in Table I1 and Triton X-100 and X-114 in (5) R. C. Meade and R. Stiglitz. I t i t . J . Appl. Radial. Isotopes, 13, 11 (1962).

A technique has been developed for the measurement of lead in gasoline in the range 0.002 to 5 g/U.S. gal. The method is based on the use of Campton Scattering as an internal standard, and on a comparison of the unknown with a blank and with a standard solution. A correction procedure has been devised which takes into account the dependence of the analysis on the carbon‐hydrogen ration of the gasoline. The method has an accuracy, for a single measurement, of ± 0.002 at the 0.002 g/U.S. gal. level to ± 0.1 at the 5 g/U.S. gal. level.