red

(red )

A primary color of the spectrum that, when added to blue, forms purple, and when added to yellow, forms orange.

Congo red

An odorless red-brown powder used in testing for amyloid. In polarized light, amyloid treated with Congo red produces a green fluorescence.

cresol red

An indicator of pH. It is yellow below pH 7.4 and red above 9.0.

methyl red

An indicator of pH. It is red at pH 4.4 and yellow at 6.2.
CAS # 493-52-7

phenol red

SEE: Phenolsulfonphthalein.

scarlet red

A red azo dye used to stimulate healing of indolent ulcers, burns, wounds, and so on; in histology, used as a stain.
SYN: SEE: rubrum scarlatinum

vital red

A stain used in preparing tissues for microscopic examination.