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DOUGLAS 0. SMITH Guilford High School Rockford, Illinois 61 1 1 1
Bent Thermometer
C02-Insecticide
Tim Kruger' reports a n ingenious method to reduce the breakage of thermometers. He analyzed the problem and felt the greatest number of thermometers were broken when they rolled off tables. The second most common accident occurred when thermometers were put into their protective tubes and subsequently slid straight through when the end -plugs fell out. The proposed solution is to heat the thermometers and put a slight hend around the 85OC mark. The method used is the same as bending glass
Australian Scientists are trying aneat method to control insect infestations while grain and seeds are being shipped by rail. By using Dry Ice, the carbon dioxide concentration was raised above 35%which made the gas an insecticide. After a four (4) day run, no live insects were found-and most important, there was no insecticide residual.
(I) use a "fish tail" flame spreader with a Bunson burner (2) rotate the thermometer slowly in the blue Bunson flame,
and
(3) give the thermometer a slight bend when the glass gets soft. Then set it aside to coal.
EDITOR'S NOTE: In comparing hent thermometers with unbent ones, we found the range of variance to heating and cooling in water haths was the same. In addition to reduceing the amount of rolling, the hent thermometers fit tighter in their plastic storage containers. This most definitely will reduce the thermometers passing straight through the plastic containers. In your experimenting, do not become over zealous in the of hend as you may seal off passage for the mercury. a two degree hend would be a good place to start. *Kruger, Tim, School Science Reuiew, 60,212, (1979).
742 1 Journal of Chemical Education
Alternative'
'Scsiro Seifile, 4 , 3 (November 1978)
Sodium and Water The reactivity of sodium with water is always an interesting demonstration for students. No doubt you are familiar with the fact that by utilizing the overhead projector the reactivity is more easily seen by the students. The usual procedure is to place a sheet of clear acetate on the overhead stage and then place a Petri dish with water in i t on the acetate sheet. Quite often after we place the sodium in the water, the sodium will go to the side of the container and stay there. G . M. Race' suggests that a drop of detergent added t o the water will prevent the sodium from sticking to the walls. If a drop of phenolphthalein solution is secretly added to the water when the demonstration is repeated, the red color that trails the sodium provides the basis for an interesting discussion. If you wish to get the students to stretch their creative thoughts, have them try to figure out what must he happening to have the sodium move as much as it does.
' Race, G. M., The School Science and Review, 60,210, (1978).
