December 3, 2010
by: Ron Perkins
At first glance No-Pop Bubbles may seem like any other bubbles. While the bubble solution is a bit more viscous, one blows No-Pop Bubbles like any other bubble. The small bubble wand suspends a bubble film which, when air is blown through it, releases small bubbles into the air. These bubbles, however, are no ordinary bubbles. No-Pop Bubble solution begins as a regular soap and water bubble solution. Added to this solution is a small amount of a non-toxic water soluble polymer. When No-Pop Bubbles are first blown, the bubbles behave like ordinary bubbles. As the water evaporates from the bubble’s surface, however, an extremely thin plastic ‘bubble skeleton’ remains. It is this plastic bubble skeleton which has the properties for which No-Pop Bubbles are named.
Blow No-Pop Bubbles up into the air. Observe the colors (interference patterns) in the bubbles as they float. In approximately 10 seconds (depending on the relative humidity) the colors in the bubbles will begin to disappear. When the bubble are colorless, they may be caught on your finger without popping! Read the rest of this entry »
December 1, 2010
by: Tami O’Connor
The fire syringe sold by Educational Innovations is a wonderfully simple, yet impressive and dramatic demonstration that increasing pressure on a gas increases its temperature. The fire piston, predecessor to the fire syringe was once used as a means of kindling fire in prehistoric Southeast Asia and the Pacific Islands. The apparatus used a hollow cylinder, sealed at one end and open on the other. A piston fit snugly in the cylinder and by sharply compressing the air, the tinder would ignite. This is an example of compression ignition.
This is also the principle behind a diesel engine. Unlike gasoline engines, diesel engines do not have spark plugs. Rather, the upward movement of the piston compresses the fuel vapor and increases the temperature to the point of combustion. That forces the piston down thus turning the drive shaft.
Here is how best to operate a fire syringe:
Place the piston into the mouth of the cylinder and thread the collar back onto the syringe. Place the syringe on a sturdy table. Get a firm grip on the handle and force the piston straight down, FAST AND HARD. The compression of the air causes the temperature of the gas to rise rapidly, igniting the material at the base of the cylinder. If the compression is done too slowly the heat will dissipate before ignition will occur. This can take a little practice, so don’t be discouraged if it doesn’t flash the first time you try it. It may be helpful to prepare a few pieces of toilet paper or cotton fiber in advance. Read the rest of this entry »