The Chemistry of Powder and Explosives - Sciencemadness Dot Org

PERCUSSION PRIMERS 455
or with water containing gum arabic or gum tragacanth, with
alcohol alone or with an alcohol solution of shellac. The caps are
loaded in much the same manner that blasting caps are loaded,
the mixture is pressed down by machine and perhaps covered
with a disc of tinfoil, the anvil is inserted and pressed into place
(unless the primer is to be used in a cartridge or fuze of which
the anvil is already an integral part), and the caps are finally
dried in a dry-house and stored in small magazines until needed
for loading.
Primer A " Vl1 Primercup Anvil
composition
Cross section
Top view (2 types)
FIGURE 105. Primer Cap for Small Arms Cartridge.
For many years the standard mixture in France for all caps
which were to be fired by the blow of a hammer was made from
2 parts of mercury fulminate, 1 of antimony sulfide, and 1 of
saltpeter. This was mixed and loaded dry, and was considered
to be safer to handle than similar mixtures containing potassium
chlorate. Where a more sensitive primer was needed, the standard
French composition for all concussion and percussion primers
of fuzes was made from 5 parts of mercury fulminate and 9 parts
each of antimony sulfide and potassium chlorate.
All the compositions listed in the following table (gum or
shellac binder not included) have been used, in small arms
primers or in fuze primers, by one or another (if the great powers,
and they illustrate the wide variations in the proportions of the
ingredients which are possible or desirable according to the design
of the device in which the primer is used.
Mercury fulminate
Potassium chlorate
Antimony sulfide
Sulfur
Meal powder
Giound glass
Ground coke
Tetryl
10 0
37 0
40.0
13 0
28 0
35 5
28 0
85
485
24 4
26.2
4
2
3
5
5
9
3
1-H 2
2
3
3
110
52 5
36 5
32
45
23
1G5
, r >0 0
33 5
7 19 0
21 3Ii 0
17 43 0
2.',
5
23