Further Uses of Black Powder

Whilst the 75 15 10 formula corresponds to one of the quickest and most vigorous of the gunpowder compositions, a slower form is required for blasting (as detailed in Table 1.2). 

This criterion is satisfied by a reduction in the potassium nitrate content, which also results in a slight reduction in cost. 

Apart from its unique property of burning quickly at relatively low confinement it is not prone to detonation. Under normal conditions the maximum rate of explosion is about 500 ms In the absence of moisture, gunpowder in also extremely stable. It has been documented that until World War I it was the practice of the French Army to preserve any batches of gunpowder that had proved especially good. These were used in time train fuses and it was claimed that some batches so preserved dated from Napoleonic times. 

Perhaps the most unusual modern application of potassium nitrate-based powders is in the fire protection industry. The white smoke mainly consists of potassium carbonate and this has been found to have fire extinguishing properties due to the way in which the potassium salt in the smoke interferes with the combustion chemistry of a fire. 

The generally accepted mechanisms for the suppression of fires and explosions by alkali metal salts such as potassium chloride, KCl potassium bicarbonate, KHCO3 and potassium carbonate,K2C03 in the form of dry powders or aerosols (smokes) involve heat absorption, endothermic decomposition and radical recombination. 

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