or ., n. (Chem.) A white or yellowish white crystalline substance, C20H14O4, formed by condensation of the anhydride of phthalic acid and phenol. Its solution in alkalies is brilliant red, but is decolorized by acids. This reaction, being very delicate, is used as a pH indicator. It is sometimes used as a laxative in veterinary medicine. [ Webster 1913 Suppl. +PJC ]
n. [ See Phthalic. ] (Chem.) One of a series of artificial organic dyes made as condensation products of the phenols with phthalic acid, and well represented by phenolphthalein. Their alkaline solutions are fluorescent. [ 1913 Webster ]
Phenol phthalein, a white or yellowish white crystalline substance made from phthalic acid and phenol. Same as phenolphthalein. [ 1913 Webster + PJC ]
(n) a laxative used in many preparations under various trade names; also used as an acid-base indicator in titrations involving weak acids and strong bases because it is brilliant red at high alkalinity and colorless below pH 8
(n) a yellow dye that is visible even when highly diluted; used as an absorption indicator when silver nitrate solution is added to sodium chloride in order to precipitate silver chloride (turns pink when no chloride ions are left in solution and negative fluorescein ions are then absorbed), Syn.resorcinolphthalein, fluoresceine, fluorescent dye
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