Perform These STARTLING STUNTS with DRY ICE (Oct, 1932)
Perform These STARTLING STUNTS with DRY ICE
by DALE R. VAN HORN
Dry ice, which might be called frozen carbon dioxide, lends itself to the performance of some mysterious and startling stunts. As told in this article, it will fire off a toy cannon, propel a model boat, make a spoon squeal like an assassinated pig, and cause a rubber band to writhe as in a terrible spasm of pain.
DRY ICE, or carbon dioxide in solid form, is an exceedingly interesting substance. We know it best as the gas that adds sparkle to our drug fountain drinks. But as a solid, it’s something else again, unique in several ways. For instance, carbon dioxide cannot exist as a liquid at normal atmospheric temperatures. It must be either a gas or solid. Only at temperatures below 31 degrees Centigrade can it exist as a liquid.
A couple of years ago it cost something like 20 cents a pound to manufacture dry ice. Today the cost has dropped to 5 cents or less and it is freely predicted that in a short time it will be competing with ordinary ice for commercial purposes. Dry ice is intensely coldâ€”authorities at the Nebraska University arriving at a temperature of 108 degrees below zero!
The substance is chiefly interesting, however, because of its unusual properties. The experimenter can do a number of unusual stunts with a pound, which will cost him about 15 cents and which, with some conservation, will last half a day.
Few of us have experienced the novelty of seeing frozen or solidified mercury in a thermometer. Mercury solidifies at about 40 degrees below zero. Yet you need only make a slight depression in a cake of dry ice, pour in a large drop of mercury and in 5 seconds, or 10 seconds at most, the liquid metal becomes solid and resembles solder!
Here is opportunity for the conjurer to exploit a new trick. He may freeze a bit of mercury out of sight on a piece of dry ice, hold it up to view, and with a few magic words, melt the metal in his hand. But the words must come fast for the metal will not long remain a solid in the human hand.
At any temperature above 108 degrees below zero, dry ice is continually turning to gasâ€”which is the same as saying that gas is passing off constantly. And as a solid turns to gas, pressure is created. This feature of dry ice permits the use of a simple cannon that will appeal to the youngsters. Based on the same principle and acting similar to the old fashioned soda-vinegar-bottle arrangement, the use of dry ice is much more satisfactory. One test with cork and bottle showed that three small pieces placed therein would blow out the cork more than 35 times.
Dry Ice Cannon
You can quite easily build the cannon as illustrated in Fig. 1. The barrel is a short length of seamless steel conduit about 5/8-inch in diameter and 4 inches long. A block of 2 by 4 inch material was cut out with the band saw and a hole bored in the frame for the barrel. To seal the end of the tube, 6 hack saw cuts 1/2 inch deep were made and the pieces bent over on each other, then solder sweated over the end to render it gas tight.
If you wish, you can affix small wheels to the four corners of the cannon carriage. Get a cork that will snugly fit the end of the barrel, then drive in a small nail or needle, and sand off the front end of the cork to make it conical.
Loading the Barrel To use the cannon, break up a number of small pieces of dry ice and drop them to the bottom of the barrel, then wet and insert the cork. The ice should not extend more than half way up the barrel or the cork will freeze in place. In a few moments the cork will be blown out with a good report and accompanied by a puff of the white gas which makes the discharge quite realistic. And if the cannon is aimed at a wooden or cloth target, the cork will stick in place.
A spectacular effect is created by setting a glass half full of water in front of a black background and throwing a spot light upon it. (See Fig. 2.) Then drop in a fair sized piece of dry ice. Instantly the water bubbles violently and the characteristic white gas fills the tumbler and falls to the. table, much as would water. Carbon dioxide has a molecular weight of 44 as compared with 28.8, the molecular weight of air. It is this much greater density that caused the gas to tumble downward so rapidly.
Another conjurer’s trick is to put a little water on a brick, block of wood or some other heavy substance, set an empty tumbler upon the wet spot, then drop some Â¦ dry ice in the glass. In a short time the two articles will freeze fast and the brick or block can be lifted by raising the glass. The trick is illustrated in Fig. 4.
You can make an ordinary rubber band do the unbelievable by placing it around or under a block of dry ice. After a few moments it is removed, and to the amazement of everyone, the rubber is rigid and nonflexible. See Fig. 6. Soon, however, it will begin to thaw out, and its gyrations and squirmings are interesting indeed, as it assumes its normal length and shape.
Press an ordinary spoon on a piece of dry ice, as demonstrated in Fig. 5, and it will sing like a canary or squeal like a stuck pig. What happens is this: The warm, smooth surface causes gas to be liberated quickly and it is this escaping gas that sets up vibrations in the spoon.
Dry Ice As a Boat Engine
Another interesting use of the power created by dry ice evaporation, is for propelling a small boat. The hull should be small and light. A block of balsa will be best, although white pine will also work well.
Make a hull, 3 inches beam and 12 inches long, as shown in Fig. 3. In the center, just back of the middle, hollow out a hole in which a half pint lacquer filler can may be seated. Bore a small hole from the deck top just back of this hole, to the stern just under the water line, then insert a 3/16 inch diameter copper tubing. Form a goose neck at the front end of the tube and solder this to a hole made in the can top as shown.
The stern tube end should protrude about 2 inches. Flatten this to a thin slit, but do not close entirely. Make sure that the can cover will seat air tight, then drop in a number of pieces of dry ice, just small enough to pass through the hole. This done, screw on the cap tightly and set the boat in the water.
Fuel Lasts Several Minutes
The gas shooting from the tube and acting against the water will send the boat forward and the action will continue for several minutes with one filling of “fuel.” If the slit in the tube is too large, force it smaller, for a tiny jet of the compressed gas will drive the boat faster than a large jet under almost no pressure. You can add a simple rudder up front if you wish the boat to have this accessory.
It is suggested that you buy your dry ice from the nearest manufacturer. It can be shipped with but little shrinkage. Dry ice is very widely used as a refrigerant in ice cream trucks, and your local dealer will be able to supply you, or to inform you of the nearest source of supply.
Dry ice can be “made” by turning a cylinder of carbon dioxide upside down and opening the jet a little. Liquid runs out and a portion of it turns to snow which can be pounded into a wooden form which will cake it into dry ice.