X·ray studies have been made of a number of carbon .blacks, prepared under different con· ditions, and subject to various heat treatments. The patterns were made in evacuated cameras, using Cu Ka radiation monochromated by reflection from rocksalt. The patterns consist of crystalline reflections (001), and two·dimensional lattice reflections (hk). The structure is one of true graphite layers arranged roughly parallel and equidistant, but otherwise completely random. The dimensions within a layer are the same as in graphite; the layer separation is somewhat larger than in graphite. The effect of heat treatment is to increase the size of the parallel layer groups. At graphitization the material changes discontinuously to the crystalline graphite structure. The usual carbon black is not finely divided graphite. Small angle scattering studies indicate the existence of clusters a few hundred angstroms in size. It is these clusters which are measured by microscope counts, by the electron microscope, and by surface areas, rather than the much smaller parallel layer groups.

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X-ray diffraction patterns have been made of three samples of soda-boric oxide glass of the following molal compositions: 0.114 NaaO, 0.225 Na20, and 0.333 NazO. The patterns were made in an evacuated camera, using MoK Q radiation monochromated by reflection from rock salt. Radial distribution curves for the three compositions were obtained by Fourier analysis. The first peak of the distribution curves is due to the boron-oxygen separation. The distances are 1.37, 1.42, and 1.48A. From the peak areas, the number of oxygens about a boron is found to be 3.2, 3.7, and 3.9. The continuous change, both in interatomic distance and number of surrounding oxygens, indicates that the borons are partly in triangular and partly in tetrahedral coordination, the fraction in the latter increasing with increase of soda. Six oxygens about each sodium at 2.4.A and from five to six oxygens about each oxygen a t 2.4A are consistent with the distribution curves. The resuits can be interpreted in terms of a random network picture of vitreous soda-boric oxide, in which the borons are bonded either to three or four oxygens and the sodium atoms are randomly distributed in holes in the boronoxygen network. Maxima and minima in the physical properties of glasses containing boric oxide and soda are explained in terms of the ability of the boron atom to change to tetrahedral coordination when some oxide such as NazO is present to supply the necessary extra oxygen

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X-ray diffraction patterns have been made of two lime-phosphate glasses with compositions of 23% and 28% of CaO by weight, and of one lime-borate glass with 25% o f CaO. Fourier analyses of these patterns were carried out, and the radial distribution curves were plotted. In the lime-phosphate glasses, each phosphorus is tetrahedrally bonded to 4 oxygens at a distance of 1.57 A, and each oxygen is bonded to either 1 or 2 phosphorus atoms. The calcium ions, Ca++, are situated in the holes in the phosphorusoxygen network and have about 7 oxygen neighbors. In the lime-borate glass, some of the borons are triangularly bonded to 3 oxygens, and the others are tetrahedrally bonded to 4 oxygens.

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