Fulminating compounds are compositions which detonate with great force by a blow or by friction.

Many metals form such compounds which are not used in the fabrication of percussion powders, but we think it will interest the reader to know how they are made.

Fulminating Antimony

i. Take -Tartar emetic . . 100 parts. Powdered charcoal • 3 "

Triturate together, put the mixture into a crucible filling it 3/4 full, cover with a layer of charcoal, lute on the cover, expose three hours to a strong heat in a reverberatory furnace, and let it cool six or seven hours. Transfer the solid contents as quickly as possible to a wide-mouth stoppered bottle, where after some time it will spontaneously crumble down into a powder.

II. Take -Antimony • • 100 parts. Carburettcd cream tartar 75 " Lampblack . . 12 "

Operate the calcination as above.

When the above processes are properly conducted, the resulting powder contains potassium and fulminates violently in contact with water. A piece the size of a pea introduced into a mass of gunpowder, explodes on being thrown into water, or its being moistened in any other manner.

Fulminating Bismuth

Take-Bismuth • . . 120 parts. Carburetted cream tartar 60 " Nitre 1 part.

Operate as above.

It is very rich in potassium, and very ex-plosive.

Fulminating Copper

Digest precipitated copper with fulminate of mercury or silver, and a little water. It forms solid green crystals that explode with a great flame.

Fulminating Gold

1st Take: Recently precipitated peroxide of gold, and digest it for 24 hours in strong ammonia. Dry the resulting fulminate in the open air, or at a temperature below 180°, care being taken to avoid the slightest friction, lest it should explode. It is a deep olive-colored powder.

2d. Digest the terchloride of gold in an excess of ammonia. It is a brownish-yellow powder.

3d. Dissolve gold in tbe following: aqua regia, sal ammoniac, 4 parts; nitric acid 12 to 16 parts, and precipitate with a solution of carbonate of potash.

This compound can be safely made only in very small quantities at a time. Without great care it explodes with violence. This is caused by the slightest friction on sudden increase of heat Its fulminating properties may be destroyed by boiling it in pearlash, lye, or weak sulphuric acid; and by heating the residue after washing it in water pure gold will be obtained.

Fulminating Platinum

Treat the sulphate of platina with an excess of ammonia. It is similar to the gold salt.

Fulminating Zinc

Operate as for the fulminating copper; digest together fulminate of silver, zinc filings, and a little water.

Fulminating Silver

1. Digest oxide of silver (recently precipitated and dried by pressure between bibulous paper) in concentrated ammonia for 12 or 15 hours; pour off the liquid, and cautiously dry the black powder in the air in divided portions. The decanted ammoniacal liquor when gently heated yields on cooling small crystals, which possess a still more formidable power of detonation than the black powder, and will scarcely bear touching, even while under the liquid.

2. Dissolve chloride of silver in strong ammonia, cautiously add pure potash in fragments, and when effervescence ceases decant the fluid portion, and wash and dry the powder as before. It is slightly less powerful than the last.

3. Pour one ounce of alcohol on 100 grains of powdered nitrate of silver, previously placed in a capacious flask or beaker glass, and shortly afterwards add one ounce of strong nitric acid. As soon as all the powdered nitrate assumes the form of white clouds, add cold distilled water enough to suspend the ebullition. Collect the powder on a filter, and proceed as before.

4. Take 50 grains of metallic silver, dissolve it in 3/4 ounce of nitric acid at a specific gravity 1.37, and add to the solution still hot, 2 ounces of alcohol, and apply heat until reaction commences; the fulminate slowly separates from the hot liquid under the form of small, brilliant, white, crystalline plates, which after being slightly washed with a little cold distilled water, are distributed upon separate pieces of filtering paper, in portions not exceeding 1 or 2 grains, and left to dry in the air. When dried, the papers are carefully folded, and preserved in boxes or bottles.

5. Take 1 part silver, and dissolve it in 10 parts of nitric acid at a spec. grav. 1.37, add the solution to 20 parts of alcohol at 85°, apply gentle heat till the liquid begins to boil, remove from the fire and set aside to cool. The fulminate of silver deposits in lustrous snow white, acicular crystals, and when washed and dried, equals in weight that of the silver employed.

The fulminate of silver occurs either in the form of a dark colored powder, or small brilliant, acicular crystals or crystalline plates, according to the mode of preparation. It dissolves in 36 parts of boiling water, but the solution deposits the greater portion of the fulminate as it cools. It is one of the most dangerous substances for which we are indebted to chemistry. It explodes with unpa-rallelled violence by the slightest friction or percussion, or when touched by sulphuric acid. This occurs even when it is moist, if it is pressed by a hard body, and when dried, the touch of a feather is often sufficient to explode it. Its explosive tendency is so great that it can hardly be made, handled, or kept with safety.