The Chemistry of Powder and Explosives - Sciencemadness Dot Org

456 PRIMARY EXPLOSIVES, DETONATORS, AND PRIMERS
A non-fulminate primer composition is probably somewhat
safer to mix than one which contains fulminate. It contains no
single substance which is a primary explosive, only the primary
explosive mixture of the chlorate with the appropriate combustible
material, or, more exactly, the explosive which exists at the
point of contact between particles of the two substances. For a
non-fulminate primer to perform properly, it is necessary that
the composition should be mixed thoroughly and very uniformly
in order that dissimilar particles may be found in contact with
each other beneath the point of the anvil and may be crushed
together by the blow of the trigger. It is not absolutely essential
that fulminate compositions should be mixed with the same uniformity.
Even if no fulminate happens to lie beneath the point
of the anvil, the trigger blow sufficiently crushes the sensitive
material in the neighborhood to make it explode. For mechanical
reasons, the ingredients of primer composition ought not to be
pulverized too finely. 64
Several non-fulminate primer compositions are listed below.
Potassium chlorate
Antimony sulfide
Lead thiocyanate
Lead peroxide
Cuprous thiocyanato
TNT
Sulfur
Charcoal
Ground glass
Shellac
50
20
25
5
50 54
26.31
8 76
1239
200
Sulfur ought not to be used in any primer composition, whether
fulminate or non-fulminate, which contains chlorate unless an
anti-acid is present. In a moist atmosphere, the sulfuric acid,
which is inevitably present on the sulfur, attacks the chlorate,
liberating chlorine dioxide which further attacks the sulfur, producing
more sulfuric acid, and causing a self-catalyzed souring
which results first in the primer becoming slow in its response
to the trigger (hang fire) and later in its becoming inert (misfire).
It is evident that the presence of fulminate in the composition
will tend to nullify the effect of the souring, and that it
64 Cf. Emile Monnin Chamot, "The Microscopy of Small Arms Primers,"
privately printed, Ithaca, New York, 1922.
67
15
16
2
60
30
3
7
.
53
17
25
5