| Weidel, Hugo | <person> Austrian chemist, 1849-1899. See: Weidel's reaction. (05 Mar 2000) |
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| Weidel's reaction | A reaction showing the presence of xanthine; a solution of the suspected substance in chlorine water with a little nitric acid is evaporated in a water bath, and then exposed to the vapor of ammonia; the presence of xanthine is indicated when a red or purple colour develops. (05 Mar 2000) |