DEMONSTRATION NOTES F ~ o mtzme to time, ztems such as the following whzch do not requzre a full half page, wzll be lzsted together. Some of them w2l be modzjicatzons of pveuiously pnbltshed demonst~atzons,zn whtch case it zs suggested that they be clipped and attached to the pertinent experiment, MONOCLINIC SULFUR CRYSTALS
Sture Skyle, Teachers Training College, Kristianstad, Sweden, suggests the use of turpentme as a solvent for sulfur from which the sulfur may be recrystallized in the prisnmtic or monoclimc form, Such a solution saturated at the inelting point of sulfur ~111,upon cooling, deposit the sulfur as long needle-like crystals. These grow in prism a t ~ cform even belox the transition point. Since turpentine can be heated a t temperatures above the melting point of sulfur, filtration is not necessary. The uudissolved sulfur melts and sinks so that the solution becomes quite transparent. Mixtures of turpentine and kerosene vill also senre. The advantages over carbon disulfide in terms of comfort and safety are obvious. FOG FORMATION
Professor John E. Bei~soi~, Gettysburg College, suggests an elahoration of Dr. Alyea's den~onstration("Tested Demonstrations,'' 5th ed., JOCRNAL OF CHEMICAL EOUCATIOF, Easton, Pa., 1962, p. 21: 97,) on fog formation. A lighted cigarette IS held close to the stopcock arm leading to the air. The flask is vented briefly to introduce a small, almost invisible amount of smoke. When the flask is again evacuated, a dense cloud will form.
P,i~"mti< sulfur grown in turpentine sol" tion.
DEMONSTRATION NOTES OXYGEN IN AIR
An experiment or den~onstration that reputedly show? that air is composed of oxygen occurs iu many texts, manuals, and other publications as follows. "A burning candle is supported in a large, flat dish containing water. A glass bottle or jar is inverted over the candle with the opening below the water level. After the candle IS extinguished, water rises in the jar." It is frequently stated that this provides evidence concerning the composition of the air. Dr. Joseph Glanz of 87-81 146th Street, Jamaica 35, New York, points out that if the data corresponds to a loss in volume of 20%, it is due to a fortuitous combination of compensating errors and that the explanations given are usually completely erroneous due to the following factors: When the candle 1s burning, the gases in the Jar are heated well above room temperature and wdl contract greatly on cooling. There is usually a loss of gas from the system due to the expan~ionof gases heated by the candle flame Combust~onunder these c~rcumstances 18 incomplete As oxygen 1s consumed, carbon dioxide is produced In equal volume. Carbon diox~deis not very soluble in water.
See also JOHN H. ROSENGREN, "Old Experiment-New Twist," Elementa~y School Science Bulletin, National Science Teachers Association, Washington, D. C., Yov. 1962, p. 10, and H. N. ALYEA,"Tested Demonstrations in Chemistry," 5th ed., JOURXAL OF CHEMICAL EDUCATION, Easton, Pa., 1962, p. 18: 2-4. CHEMILUMINESCENCE IN ELECTROLYSIS
Fidel Villarreal and Octavio GarcXa of the Institute Tecnologico de Monterrey of Monterrey, N. L., M6xic0, use the oxidation taking place at the anode in an electrolysis cell in place of hydrogen peroxide in performing the usual chemiluminescence demonstration with luminol (3-aminophthalhydrazide). The usual variations including the addition of ice to emphasize the "cold" aspect of the phenomena and the extinguishing of luminescence by acidifying the ~olution may be performed in the electrolytic cell as they are with the more conventional demonstration. See H. N. A L Y E ~"Tested , Demonstrations in Chemistry," 5th OF CHEMICAL EDUCATION, Easton, Pa., ed., JOURNAL 1962, p. 7: 2-14, and also HUNTRESS, E. H., STANLEY, L. N., AND PARKER,A. S., THIS JOURNAL, 11, 143 (1943) Jo",,,~ 01cham,cd Ed"~oL.0" , June IQm
