PURPOSE:To provide measurability for the dosage of near ultraviolet rays among the solar beams by using a preparation of polyvinyl acetate or its saponide, biologens, and hydrophilic 2-hydroxybenzophenons. CONSTITUTION:Together with biologen hydrophilic 2-hydroxybenzophenon is dissolved compatible in polyvinyl acetate or its saponide, and this preparation is turned into a film. Thus a luminous meter is accomplished, with which the degree of sun burn is measurable. Example of 2-hydroxybenzophenons nuclearly substituted with hydrophilic radical is such a compound as formed through the process that one or more hydrogen atoms in bond with an aromatic ring of 2-hydroxybenzophenon are substituted with one or more sorts of hydrophilic radicals, for example, hydroxyl radical, carboxyl radical, and amide radical. As biologen, inorganic acid such as chloric acid, bromic acid is used as the additive to bipyridyl. The luminous meter thus produced changes its color from clear to pale blue, blue, bluish violet, and deep violet according to the dosage of near ultraviolet rays. Thereby the dosage of radiations can be determined by reference to a standard colorimatric table.
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