S + O2 --> SO2
H. N. Alyea and F. B. Dutton, Eds.,"Tested Demonstrations in Chemistry", 6th ed., Journal of Chemical Education, Easton, Pennsylvania (1965) p.42.
L. R. Summerlin, C. L. Borgford, and J. B. Ealy,"Chemical Demonstrations A Sourcebook for Teachers",Vol. 2, American Chemical Society, Washington, DC, (1987) p.165.