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Single crystals of oxalic acid dihydrate are difficult to grow from pure water solution, but good single crystals of the material may be obtained by growth from mixtures of acetone and water. The solvent markedly affects the crystal habit. Crystals grown in mixtures of acetone and water develop the prismatic habit, while those grown in water alone develop the tabular or equant habit. The forms {001}, {110}, and {101} predominate in all cases. Single crystals of anhydrous oxalic acid may also be grown from solution in glacial acetic acid, although specimens more than 2 centimeters in length are difficult to produce. down their lengths, the density and calcium carbonate content determined on 55 Abstract. Three South Atlantic deep sea cores have been dated by the carbon-14 technique, and rates of accumulation of clay and calcium carbonate have been determined. The highest eupelagic clay rates for the Atlantic found to date are in the Argentine Basin, and the lowest are on the Mid-Atlantic Ridge. Abstract. Three South Atlantic deep sea cores have been dated by the carbon-14 technique, and rates of accumulation of clay and calcium carbonate have been determined. The highest eupelagic clay rates for the Atlantic found to date are in the Argentine Basin, and the lowest are on the Mid-Atlantic Ridge.

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The results of etch-pit and diffraction topographic studies on ammonium dihydrogen phosphate (ADP) are reported. These studies were carried out on specimens sectioned by abrasive wheel and string-saw from large single crystals grown from aqueous solution. The two characterization methods are shown to be in approximate one-to-one correspondence in the case of sections produced by abrasive sawing. Absence of both etch pits and topographic images in sections made by string-sawing of material well removed from the seed region is taken to indicate that this material is dislocation-free. Preliminary results on the plasticity of ADP are reported.

Microscopic observations of growth layers and etch pits on ammonium dihydrogen phosphate crystals reveal screw dislocations on the {100} face generating elliptical spirals that change rapidly but reversibly to rectangular shape when chromium-ion impurity is added. The effects of the impurity on crystal habit are judged to be secondary to changes in the morphology of the growth layers. No sources of growth are observed on the {101} faces; the layers spread inward from the edges and at times are mutually annihilating so that, temporarily, no steps are observed. Similar behavior is recorded for the {1011} faces of NaNO(3).