diacetyl dioxime:

Colorless crystals; melting point, 238°-240°C. It is soluble in alcohol, ether, and solutions of alkalies. With nickel salts it yields a red insoluble precipitate of nickel dimethylglyoximate, (C₄H₇O₂N)₂Ni, which is a chelate compound. Because of this, dimethylglyoxime is used for the qualitative and quantitative determination of nickel. In 1905, L. A. Chugaev suggested the use of dimethylglyoxime as a specific reagent for nickel. Dimethylglyoxime is made by treating diacetyl with hydroxylamine.