To make the mixture of the fulminate of mercury with the nitre, they generally take the latter one into small pieces, and grind it with the fulminate. To manufacture in such a manner is very dangerous, also it is very important to observe all the directions previously given, and which consist in the use of the nitre previously reduced to a fine powder, and being careful to slightly humect it after having spread it on a large surface. This done, throw on it the fulminate, which is mixed with a wooden or horn spatula. The grinding is effected on a polished marble table, three feet by six. Black marble is preferable to white, because the powder remaining on some places can be more easily distinguished.

To effect the grinding, begin to raise the substances with the spatula, and terminate the operation with a wooden roller. The best wood to use is the boxwood. This operation must be done very carefully, and the grinding must be slightly and carefully done to avoid detonations, which are, of course, more dreadful as the quantities arc more considerable. The marble and the paste must always be damp, for after a certain degree of desiccation, the explosion will be unavoidable, even with a very light pressure. It is well understood that it is necessary to operate on small masses at a time, and divide into small fractions the prepared fulminate. The quantity of nitre is half that of the fulminate, the mixture thus consisting: 2 parts of fulminate for 1 of nitre.

The mixture being made, take the paste with the spatula, but whatever be the care taken, it is impossible not to leave on the table a little fulminating matter that the desiccation will render explosive. We shall repeat hero what we have said about matches. The table must be immediately washed with a sponge, and as the sponge itself will have adhering to it fulminating matters, wash it well in a pail of water. It will be dangerous to crush directly the little grains obtained during the above operation. By thus operating, accidents can bo avoided. The following is the way to treat those grains without any danger. Wet with a sponge a varnished jar, throw into it the damp powder, some mist of the same operation, then the grains that you cover with some damp powder.

Leave the mixture all night, and the next day, raise the matter with the hand, and with a spatula carefully operate the mixture.

That paste is divided on blotting paper, and carried to the drier.