The Chemistry of Powder and Explosives - Sciencemadness Dot Org

TESTING OF DETONATORS 421
pressed. In February of the next year AVohler was granted a
French patent 26 in which lead azide was specifically mentioned,
but the use of this substance had already been anticipated by
the patent of Hyronimus. Lead azide was soon afterwards manufactured
commercially in Germany and in France, and compound
detonators containing this material were used fairly generally
in Europe at the time of the first World War. A few years
later the manufacture of lead azide detonators was commenced
in the United States. In this country compound detonators having
a base charge of tetryl and primed with 80/20 fulminate-chlorate
or with lead azide have been superseded in part by detonators
loaded with a more powerful high-explosive charge of nitromannite,
PETN, or diazodinitrophenol and primed with lead azide,
alone or sensitized to flame by the addition of lead styphnate or
tetracene, or with diazodinitrophenol as the primary explosive.
Testing of Detonators
Among the tests which are used for determining the relative
efficiency of detonators, 27 the lead block or small Trauzl test, in
which the detonators are fired in holes drilled in lead blocks and
the resulting expansions of the holes are measured, and the lead
or aluminum plate test in which the detonators are stood upright
upon the plates and fired, and the character and extent of the
effects upon the plates are observed, have already been mentioned.
28 The first of these gives results which are expressible by
numbers, and in that sense quantitative, and it is evident that
both methods may be applied, for example, to the determination
of the minimum amount of primary explosive necessary for the
initiation of a high explosive, for both show notably different
effects according as the high explosive explodes or not. Another
useful test is the determination of the maximum distance through
which the detonator is capable of initiating the explosion of some
standard material, say, a piece of cordeau loaded with TNT. In
the nail test, 29 a wire nail is fastened to the side of the detonator,
the detonator is fired, and the angle of the bend which the ex-
26 French Pat. 387,640 (February 28, 1908).
27 Clarence Hall and Spencer P. Howell, "Investigations of Detonators
and Electric Detonators," U. S. Bur. Mines Bull. 59, Washington, 1913.
28 Vol. I, p. 26.
29 Hall and Howell, op. at., p. 25.