Whistles
A unique, whistling phenomenon can be produced by firmly pressing certain oxidizer/fuel mixtures into cardboard tubes and igniting the compositions. A detailed analysis of this phenomenon, both from a chemical and physical view, has been published by Maxwell.
A reaction that produces a whistling effect is burning intermittently from layer to layer in the pressed composition. A whistling reaction is on the verge of an explosion, so these mixtures must be cautiously prepared and carefully loaded into tubes. Large quantities of bulk powder should be avoided, and they should never be stored near operating personnel. Several formulas for whistle compositions are given in The table.
Whistle Compositionsa