Re: Volcano Demonstration Question

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From: Chuck Britton (britton@ncssm.edu)
Date: Sat May 24 2003 - 18:38:59 PDT 

Message-Id: <a05200f5ebaf5cc8d72cb@[192.168.1.101]>
Date: Sat, 24 May 2003 21:38:59 -0400
From: Chuck Britton <britton@ncssm.edu>
Subject: Re: Volcano Demonstration Question

When our daughter was in the fifth grade, the 'volcano' unit came up
but she didn't want to do the 'usual' baking soda + vinegar. She had
been caving with us and knew a LITTLE bit about the 'Carbide Lamps'
that we used.

Needless to say, the teacher was QUITE amazed when she poured a bit
of water into her model volcano and asked him to light it.

MUCH stringy, greasy soot produced along with the flames. There
probably weren't any smoke detectors or sprinkler systems in the
schools way back then.

OK, ya'll, at 9:37 AM +0930 5/25/03, Michael Michie wrote:
>I've done demonstrations with liquid soap and shaving cream to demonstrate
>the difference between shield volcanoes and stratovolcanoes respectively.
>Primarily it demonstrates the viscosity of the lava and why a lava
>containing gases is unlikely to move far.
>
>You need a baseboard with a small hole in it. You place the nozzle of the
>container (liquid soap or shaving cream in a spray can) under the hole so
>that the soap/foam can make its way through. The liquid soap should flow
>through and form a large puddle, then it will flow back out the hole, so you
>need to be over a sink or a bucket. The shaving foam will create a pile
>above the hole. When it eventually collapses it ends up looking more or less
>like the liquid soap, so you can see that air was supporting the pile.
>
>There is a problem of scale in this experiment, as shield volcanoes tend to
>be much larger than stratovolcanoes in real life. The people who first came
>up with the demonstrations were trying to avoid the thermite and ammonium
>dichromate experiments for safety reasons - both for the instructor and the
>observers. I've seen people doing the sodium bicarbonate experiment many
>times, often using red paint instead of water, or pink sherbet (that's a
>powdered version of sodium bicarbonate and citric acid with red food
>colouring; as you eat it, it fizzes in your mouth). Some people have put
>magnesium ribbon in the crater and lit it.
>
>Michael Michie
>
>PS. I don't know why Glenn can't get iron filings, he works about half an
>hour from some steelworks. 

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Chuck Britton 					Education is what is left when
britton@ncssm.edu 	       		you have forgotten everything
North Carolina School of Science & Math		you learned in school.
(919) 416-2762					Albert Einstein,        1936

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