Sulfide Compounds
Several metallic sulfide compounds have been used as fuels in pyrotechnic compositions. Antimony trisulfide, Sb 2S 3 , is a reasonably low-melting material (m.p. 548°C) with a heat of combustion of approximately 1 kcal / gram. It is easily ignited and can be used to aid in the ignition of more difficult fuels, serving as a "tinder" in the same way that elemental sulfur does. It has been used in the fireworks industry for white fire compositions and has been used in place of sulfur in "flash and sound" mixtures with potassium perchlorate and aluminum.
Realgar (arsenic disulfide, As2 S2) is an orange powder with a melting point of 308°C and a boiling point of 565°C. Due to its low boiling point, it has been used in yellow smoke compositions (in spite of its toxicity!) , and has also been used to aid in the ignition of difficult mixtures. The use of all arsenic compounds -- including realgar - is prohibited in "common fireworks" (the type purchased by individuals) by regulations of the U. S. Consumer Product Safety Commission.