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A dyestuff extracted from certain lichens (Roccella tinctoria, Lecanora tartarea, etc.), as a blue amorphous mass which consists of a compound of the alkaline carbonates with certain coloring matters related to orcin and orcein.

rming salts with acids, turning to brown several vegetable yellows, and changing reddened litmus to blue. Fixed alkalies, potash and soda. -- Vegetable alkalies. Same as Alkaloids. -- Volatile alkali, ammonia, so called in distinction from the fixed alkalies.

Exhibiting or producing two colors, as substances which in the color test may change red litmus to blue and blue litmus to red.

A red substance obtained from litmus.

See Litmus.

Having neither acid nor basic properties; unable to turn red litmus blue or blue litmus red; -- said of certain salts or other compounds. Contrasted with Ant: acid, and Ant: alkaline. Neutral axis, Neutral surface (Mech.), that line or plane, in a beam under transverse pressure, at which the fibers are neither stretche…

A kind of lichen (Lecanora parella) once used in dyeing and in the preparation of litmus.

agent which changes color in some specific way when acted upon by those substances; thus, litmus paper is turned red by acids, and blue by alkalies, turmeric paper is turned brown by alkalies, etc. (b) (Law) An instrument admitted as a standard or comparison of handwriting in those jurisdictions in which comparison of…

Litmus. [Obs.]