The sensitivity of firework compositions

The factors which have a large influence on sensitivity are two the kind of oxidizers and the fuels(oxidizing agents). The sensitivities may be classified simply as in Table 28 according to the results of many experiments. 

Fuel Red phosphorus Realgar Antimony tri- Sulphur Milk sugar Alumin- ium Charcoal 

Generally speaking, the composition which is sensitive to shock is also sensitive to friction. On the contrary the one which is insensitive to shock is also insensitive to friction, but there are some types which do not follow this rule a whistle composition consisting of potassium picrate and potassium nitrate is sensitive to shock but insensitive to friction the thermit compositions, especially red thermit which consists of red lead and ferro-silicon, are quite insensitive to shock but sensitive to friction. 

The ratio of the oxidizer to the fuel(by weight) also has an influence upon the sensitivity. Note however that in the case of red phosphorus, realgar, antimony trisulphide or sulphur the influence is quite small, and 

The readers perhaps notice in Table 28 the fact that, if materials which give a high sensitivity like red phosphorus, realgar, sulphur, antimony trisulphide etc. are rejected from firework compositions, firework manufacture is made much safer. In these circumstances devices are always necessary, the problem being that without these materials ignition can be difficult in fireworks. This is one of the most important themes in fireworks. 

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The sensitivity of firework compositions 28 Burning character of some fundamental compositions 29 Parachute, flags and balloons 30 Miscellaneous compositions... 

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