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Webster 1913 Edition

(rē̍-ā′jent)

Noun.

(Chem.)

A substance capable of producing with another a reaction, especially when employed to detect the presence of other bodies; a test.

Noun.

[re and agent.] In chimistry, a substance employed to precipitate another in solution, or to detect the ingredients of a mixture.

Bergman reckons barytic muriate to be one of the most sensible reagents.