R. Meyer J. Köhler A. Homburg Explosives

Silvered Vessel Test
Silvered Vessel Test
In this testing procedure the propellant sample (about 50 g) is heated
in an insulating Dewar vessel, and the rise in temperature produced by
the heat of decomposition of the powder is determined. The powder
sample is heated to 80 °C (176 °F); the time is determined in which
the powder reaches 82 °C (180 °F) by its own heat development on
decomposition.
Frey’s variant of the silvered vessel test has been in use in the
Germany. In its variant, different amounts of heat are supplied to the
electric heating elements mounted inside the Dewar flask, and the
temperature differences between the interior of the Dewar vessel and
the furnace are measured by thermocouples. A calibration curve is
plotted from the values thus obtained, and the heat of decomposition
of the propellant is read off the curve. In this way, the decomposition
temperature at a constant storage temperature can be determined as
a function of the storage time, and the heat of decomposition of the
propellants can thus be compared with each other. If the measurements
are performed at different storage temperatures, the temperature
coefficient of the decomposition rate can be calculated. (W also
Differential Thermal Analysis.)
Silver Fulminate
Knallsilber; fulminate d’argent
CNOAg
white, crystalline powder
molecular weight: 149.9
oxygen balance: –10.7%
nitrogen content: 9.34%
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Silver fulminate is prepared by the reaction employed in the preparation
of W Mercury Fulminate, i.e., by reacting a solution of silver in nitric
acid with alcohol. Like mercury fulminate, it is also toxic.
Silver fulminate is much more sensitive than mercury fulminate. Since
its detonation development distance is very short, its initiation effect is
superior to that of mercury fulminate, but the compound is too sensitive
to be used commercially.
An altogether different product, known as Berthollet’s detonating silver
(which is not a fulminate), is obtained when a solution of freshly
precipitated silver oxide in ammonia is allowed to evaporate. Its probable
formula is Ag3N. It is highly sensitive and explodes even during the
evaporation of the ammoniacal solution.