To produce mercury(II)Fulminate,a very sensitive shock explosive,one might assume that it could be formed by adding fulminic acid to mercury. This is somewhat difficult since fulminic acid is very unstable and cannot be made or bought about.
The preparation is so : Five grams of mercury is added to nitric acid (specific gravity 1.42)(not necessary) in a 100-cc. flask, and the mixture is allowed to stand without shaking until the mercury has gone into solution. The acid liquid is then poured into 90% alcohol beaker, in the hood. The temperature of the mixture rises, a vigorous reaction commences, white fumes come off, it soon begins 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, and corresponds to a good grade of commercial fulminate. It 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 fulminate is filtered off, washed several times with cold water, and stored under water and for experimental purposes; it is dried first.