Burning time black powder

Figure 2.1 Influence of pellet density on black powder burning time.

The plastic flow of sulfur is thought to be responsible for the increase in the burning time that is experienced with black powders of various pellet sizes as the pellets (or grains) are compressed to higher bulk densities. 

Delay Composition A general term for a mixture that burns at a seleeted, reproducible rate, providing a time delay between activation and production of the main effect. A fuse containing a core of black powder is an example of a delay. Highly-reproducible delay mixtures are needed for military applications, and much research effort has been put into developing reliable compositions. 

At some early time, prior to 1000 A.D., an observant scientist recognized the unique properties of a blend of potassium nitrate, sulfur, and charcoal and black powder was developed as the first "modern" high-energy composition. A formula quite similar to the one used today was reported by Marcus Graecus ("Mark the Greek") in an 8th century work "Book of Fires for Burning the Enemy"... 

Fuse A train of slow-burning powder (usually black powder), often covered with twine or twisted paper. Fuses are lit by a safety match or other hot object, and provide a time delay to permit the person igniting the device to retreat to a safe distance. 

Coal Powders. These are black powders in which charcoal is replaced by coal, as for example, in compositions developed at Pic-Arsn by Varrato (Refs 1 2). Such powders burn slower than corresponding charcoal contg BkPdrs and for this reason are suitable for use in slow-burning safety fuses or in time fuzes. By blending them with suitable charcoal pdrs, various intermediate rates of burning may be obtd... 

A sample of commercial black powder of moderately fine granulation, say FFF, may be poured out in a narrow train, 6 inches or a foot long, on a sheet of asbestos paper or a wooden board. When one end of the train is ignited, the whole of it appears to bum at one time, for the flame travels along it faster than the eye can follow. Commercial black powder is an extremely intimate mixture the rate of its burning is evidence of the effect of intimacy of contact upon the rate of a chemical reaction. The same materials, mixed together as intimately as it is possible to mix them in the laboratory, will burn much more slowly. 

This mixture is extremely powerful and very,very fast burning. Well made,with very fine ingredients, it burns about 3 times faster than commercially made black powder. It is excellent for use In aerial bombs, large or small firecrackers or any purpose where a quick violent explosion is needed. It is too rapid burning for use in any firearm, and is not suited to such use. 

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