Definition of neutral red in English:
neutral red
noun
A dark green crystalline azine dye, C₁₅ H₁₆ N₄ ·HCl, which forms a red solution in water or alcohol and is used as an acid-base indicator and as a biological stain (especially for granules and vacuoles in cells).
Origin
Late 19th century; earliest use found in Thomas E. Thorpe (1845–1925), chemist.
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