Abstract
THE absorption spectra of crystals of ergosterol and calciferol are the same as those of their solutions but for a slight alteration of wave-lengths. The changes produced in solution by irradiation in monochromatic ultra-violet light can also be produced in crystals. They can be observed by the progressive alteration from anisotropic to isotropic material in a polarising microscope. Ergosterol is transformed presumably to calciferol in light of 2967 A., but scarcely at all in 3650, 3130, and 2537 A. Calciferol, on the other hand, is stable at 3650 and 2537 A., but destroyed in 3130 A. This differs from the behaviour of solutions partly on account of the greater absorption and the formation of protecting layers on the surface of the crystals.
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NATURE, Feb. 20, 1932.
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BERNAL, J. Properties and Structures of Crystalline Vitamins. Nature 129, 721 (1932). https://doi.org/10.1038/129721a0
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DOI: https://doi.org/10.1038/129721a0
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