The preparation and properties of a semisolid nickel sulfate-sorbitol complex are described. The absorbance curve of the complex corresponds closely with that of an approximately saturated solution of hydrated nickel sulfate in water with the advantage of a two-fold increase in absorbancy index at the peak absorption. Used as a filter component it eliminates the undesirable properties of a liquid filter. A freshly made 3.5-mm thickness of complex had an average transmittance at 2850 A of 75% which showed a slight decrease after three years. An appreciable loss of transmittance after nine years arises from the development of an absorption band at 2850 A. The relationship of this band with a temperature-sensitive band in water solutions of pure nickel sulfate is discussed. The filter remains visually clear indicating that the complex has not crystallized in nine years.
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