Preparation of Mercury Fulminate

Preparation of Mercury Fulminate

Mercury Fulminate: 5 g of metallic mercury is added to 35 ml of concentrated nitric acid (d=1.42 g/ml) in a 100-ml Erlenmeyer flask, and the mixture is allowed to stand without shaking until the mercury has gone into solution. The acid liquid is then poured into 50 ml of 90% alcohol in a 500-ml beaker in the hood.

Mercury Fulminate: The temperature of the mixture rises, a vigorous reaction commences, white fumes come off, and crystals of merury(II) fulminate soon begin to precipitate. Red fumes appear and the precipitation of the fulminate becomes more rapid, then white fumes again as the reaction moderates.

After about 20 minutes the reaction is over; water is added, and the crystals are washed with water repeatedly by decantation until the washings are no longer acid to litmus. The product consists of grayish-yellow crystals.

Mercury(II) fulminate may be obtained white and entirely pure by dissolving in strong ammonia water, filtering, and reprecipitating by the addition of 30% acetic acid. The pure mercury(II) fulminate is filtered off, washed several times with cold water, and stored under water, or, if a very small amount is desired for experimental purposes, it is dried in a desiccator.

Chemistry of Powder and Explosives, by T. L. Davis, 406-407, 1941

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