product obtained, which is mercury fulminate, is 112 per cent. of the
mercury employed. Another method is to dissolve 10 parts of mercury in 100
parts of nitric acid of a gravity of 1.4, and when the solution has
reached a temperature of 54 deg. C, to pour it slowly through a glass funnel
into 83 parts of alcohol. When the effervescence ceases, it is filtered
through paper filters, washed, and dried over hot water, at a temperature
not exceeding 100 deg. C. The fulminate is then carefully packed in paper
boxes, or in corked bottles. The product obtained by this process is 130
per cent. of the mercury taken. This process is the safest, and at the
same time the cheapest. Fulminate should be kept, if possible, in a damp
state. Commercial fulminate is often adulterated with chlorate of potash.

~Detonators~, or caps, are metallic capsules, usually of copper, and
resemble very long percussion caps. The explosive is pure fulminate of
mercury, or a mixture of that substance with nitrate or chlorate of
potash, gun-powder, or sulphur. The following is a common cap mixture:--
100 parts of fulminate of mercury and 50 parts of potassium nitrate, or
100 parts of fulminate and 60 parts of meal powder. Silver fulminate is
also sometimes used in caps. There are eight sizes made, which vary in
dimensions and in amount of explosive contained. They are further
distinguished as singles, doubles, trebles, &c., according to their
number. Colonel Cundill, R.A. ("Dict. of Explosives"), gives the following
list:--

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, ch