From: Michael Michie (mmichie@ozemail.com.au)
Date: Sat May 24 2003 - 17:07:16 PDT
Message-ID: <005501c32251$9aacb110$4d020c3f@default> From: "Michael Michie" <mmichie@ozemail.com.au> Subject: Re: Volcano Demonstration Question Date: Sun, 25 May 2003 09:37:16 +0930
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.
----- Original Message -----
From: "John or Jan Lahr" <johnjan@lahr.org>
To: <webhead-l@eskimo.com>; <pinhole@exploratorium.edu>
Cc: <brendanjwatson@yahoo.com>
Sent: Friday, May 23, 2003 1:27 PM
Subject: Fwd: Volcano Demonstration Question
> If anyone has a suggestion from Brendan, please cc him as he is not on
these
> lists.
>
> Thanks,
> John
>
>
> >------------- Begin Forwarded Message -------------
> >
> >
> >From:
> > brendan watson <brendanjwatson@yahoo.com>
> > 00:19
> >
> > Subject:
> > NEIC Web Question
> > To:
> > zirbes@usgs.gov
> >
> >
> >hello Madeleine, i am a mid-high school science teacher working in Nth
> >Sumatra, in Indonesia. One of our lower school classes is doing a
> >'vulcanos' topic at present, and are building a model for such. I
> >wanted to show them the 'real' thing, with a small explosion and
> >over-flow of 'lava' from the crater. I know that there is a very safe
> >explosion that would be suitable that has been used in other schools-
> >do you happen to know what the chemicals are, for this reaction?? Would
> >be very grateful for any guidance you may provide, thanks bj
> >
> >------------- End Forwarded Message -------------
>
>
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