Sulfur Iron Whistle
The other day I was experimenting with an old copper coated scrub sponge in a Pyrex tube about 4 feet long and 2.5 inches in diameter. Normally the
sponge would glow when heated and a few seconds after removing the propane torch flame the tube would make an audible tone.
Another way to make a tone is to just hold a torch inside a tube without a grid. But oddly with a metal grid you have to heat the screen and then
remove the flame before the sound/feedback will start.
I was trying to get a howl by burning a couple of charcoal briquettes held in place by a piece of screen 1/4 of the way up the tube. This didn't work
although there was seemingly plenty of heat. I then put the old black scrub sponge above the briquettes and that didn't work either. So I decided to
just run it normally with the sponge and propane torch technique. But maybe the charcoal smoke did something to the sponge or the sponge was old, but
when I heated it, it caught fire in the center this time and continued to glow like lit steel wool. And this behavior produced a fairly loud, almost
annoying continuous howl. It reminded me of the sulfur iron whistle and it occurred to me that a piece of steel wool lit in the verticle position in
a tube would probably work as well or better than what I observed with the sponge. Extrapolating, perhaps magnesium shavings would work even better.
There are several Sondhauss tube and Rijke tube demonstrations on youtube. Sometimes Rijke tubes are called howler tubes. Maybe if I had crumbled the
glowing charcoal into a flat layer, it would have worked. There is a chimney effect that supports combustion.
http://www.youtube.com/watch?v=B7HidVyFdn8
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