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THEALLOTROPYOFSULFUR A Demonstration 8. B. BUTLER Queens College, Flushing, New York
THEfollowing demonstration that the allotropic forms of sulfur have different physical properties may he used t o supplement the usual laboratory experiment of testing solubilities with carbon disulfide. With suitable modification it may he used as a lecture demonstration or as a side-table demonstration in the laboratory. Principle. Since the melting point of rhomhic sulfur is about 113'C. and that of monoclinic sulfur is about 118"C.,if samples are heated by the vapor of boiling n-butyl alcohol (b. p. IIG°C.) it can he shown that the rhomhic form melts at a lower temperature than does the monoclinic. Method. Set up a three-necked flask with a watercooled reflux condenser. Suspend within the flask, by
means of bored stoppers in the side necks, two thinwalled tubes which contain powdered samples of the two forms of sulfur. Add to the flask a suitable quantity of n-hutyl alcohol and a few hoiling chips and heat so that the liquid refluxes gently. The rhomhic sulfur will soon melt hut the monoclinic sulfur will remain unchanged. Certain advantages are secured by presenting the demonstration during the student laboratory period devoted to sulfur. Then freshly recrystallized samples prepared by the students may he used and since the apparatus may he closely inspected by the students it can be much smaller and simpler. For safety the apparatus should he used only by the instructor.
