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signating, a dibasic acid obtained by the oxidation of naphthalene and allied substances. Phthalic acid (Chem.), a white crystalline substance, C6H4.(CO2H)2, analogous to benzoic acid, and employed in the brilliant dyestuffs called the phthaleins.

Formerly, designating an acid probably identical with phthalic acid.

Of, pertaining to, or designating, a dibasic acid of the aromatic series, metameric with phthalic acid, and obtained, as a tasteless white crystalline powder, by the oxidation of oil of turpentine; -- called also paraphthalic acid. Cf. Phthalic.

A yellowish red, crystalline substance, C20H12O5, produced by heating together phthalic anhydride and resorcin; -- so called, from the very brilliant yellowish green fluorescence of its alkaline solutions. It has acid properties, and its salts of the alkalies are known to the trade under the name of uranin.…

A red crystalline dyestuff, obtained by heating together pyrogallic and phthalic acids.

A salt of naphthalic acid; a phthalate. [Obs.]

llowish 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 an indicator.

A salt of phthalic acid.

of a series of artificial organic dyes made as condensation products of the phenols with phthalic acid, and well represented by phenol phthaleïn. Their alkaline solutions are fluorescent. Phenol phthalein, a white or yellowish white crystalline substance made from phthalic acid and phenol. Its solution in alkalies is…

An imido derivative of phthalic acid, obtained as a white crystalline substance, C6H4.(CO)2NH, which has itself (like succinimide) acid properties, and forms a series of salts. Cf. Imido acid, under Imido.

The hypothetical radical of phthalic acid.

A salt of terephthalic acid.