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Related to Phenol phthalein: methyl orange
|See under Phthalein.|
|a white or yellowish white crystalline substance made from phthalic acid and phenol. Its solution in alkalies is brilliant red, but is decolorized by acids, and as this reaction is exceedingly delicate it is used as an indicator.|
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.