AUGUST, 1991
LARGE CRYSTALS OF MONOCLINIC SULFUR MILTON G. WOLF James Madison High School, Broolrlyn, New Yo&
IN A pamphlet on sulfur which I read a couple of years ago there was included a table which listed several solvents for sulfur, among which, strange a t it appeared to me, was olive oil. The following question arose in my mind a t the time: Suppose olive oil is saturated with sulfur at the highest temperature reported, 130°C., and then cooled, mould not monoclinic sulfur crystallize out between 114.5" and 96'C., since this is t,he stable form between these temperatures? Moreover, if the solution is cooled very slowly, would not large size crystals he obtained? I did not act upon these thoughts until this year, and in the meanwhile have forgotten the name of the company to which I am indebted for the table of solubilities. As a result of employing this method outlined below I obtained monoclinic sulfur crystals which are by far the largest I have seen of this form, and although the method is time-consuming by comparison with the conventional method, I feel the reward worth the effort. PROCEDURE
Pour ground roll-sulfur into a 150-ml. beaker until it rises to a height of '/, in. Then add about 25 ml..of olive oil. Pour 350 ml. of olive oil into a 600-ml. beaker.
Partly immerse the small beaker in the olive oil contained in the larger beaker. Heat the large beaker gradually, all the while stirring the sulfur-oil mixture in the small beaker with a thermometer graduated to a t least 130°C. Meanwhile heat a large-size test tube until it feels uncomfortably warm. When the temperature of the mixture in the small beaker reaches 130°, remove the flame and pour the oil from the small beaker into the test tube, being careful not to include any undissolved liquid sulfur. Pour the oil from the large beaker slowly into a clean dry 1pint thermos bottle. Stopper the test tube and place it in the thermos bottle. The test tube will go in all the way to its flange without causing spillage of any oil from the thermos. Place some tissue paper loosely in the cap of the thermos and screw on the cap. Stand the thermos upright in a cabinet for a t least 24 hours. Remove the test tube from the thermos. Fine, long, needle-like crystals, ranging from to 1 in. in length, should be present. Since rhomhic sulfur is the only stable form below 96'C., these crystals upon standing a few days will be changed into aggregates of minute crystals of rhombic sulfur, although the over-all monoclinic form is preserved. This so-called crystalline shape is called a psendomorph.
