No. 1 contains 300 grms. of explosive per 1000. " 2 " 400 " " " " " " 3 " 540 " " " " " " 4 " 650 " " " " " " 5 " 800 " " " " " " 6 " 1,000 " " " " " " 7 " 1,500 " " " " " " 8 " 2,000 " " " " "

Trebles are generally used for ordinary dynamite, 5, 6, or 7 for gun-cotton, blasting gelatine, roburite, &c.

In the British service percussion caps, fuses, &c., are formed of 6 parts by weight of fulminate of mercury, 6 of chlorate of potash, and 4 of sulphide of antimony; time fuses of 4 parts of fulminate, 6 of potassium chlorate, 4 of sulphide of antimony, the mixture being damped with a varnish consisting of 645 grains of shellac dissolved in a pint of methylated spirit.  Abel’s fuse (No. 1) consists of a mixture of sulphide of copper, phosphide of copper, chlorate of potash, and No. 2 of a mixture of gun-cotton and gun-powder.  They are detonated by means of a platinum wire heated to redness by means of an electric current.  Bain’s fuse mixture is a mixture of subphosphide of copper, sulphide of antimony, and chlorate of potash.

In the manufacture of percussion caps and detonators the copper blanks are cut from copper strips and stamped to the required shape.  The blanks are then placed in a gun-metal plate, with the concave side uppermost—­a tool composed of a plate of gun-metal, in which are inserted a number of copper points, each of the same length, and so spaced apart as to exactly fit each point into a cap when inverted over a plate containing the blanks.  The points are dipped into a vessel containing the cap composition, which has been previously moistened with methylated spirit.  It is then removed and placed over the blanks, and a slight blow serves to deposit a small portion of the cap mixture into each cap.  A similar tool is then dipped into shellac varnish, removed and placed over the caps, when a drop of varnish from each of the copper points falls into the caps, which are then allowed to dry.  This is a very safe and efficacious method of working.

At the works of the Cotton-Powder Company Limited, at Faversham, the fulminate is mixed wet with a very finely ground mixture of gun-cotton and chlorate of potash, in about the proportions of 6 parts fulminate, 1 part gun-cotton, and 1 part chlorate.  The water in which the fulminate is usually stored is first drained off, and replaced by displacement by methyl-alcohol.  While the fulminate is moist with alcohol, the gun-cotton and chlorate mixture is added, and well mixed with it.  This mixture is then distributed in the detonators standing in a frame, and each detonator is put separately into a machine for the purpose of pressing the paste into the detonator shell.