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Re: Verify and comment, please.



This unmixing-by-particle-size behavior is well known to packaging
technologists, and can be confirmed by simple experiments. For example try
marbles and birdseed.

I remember reading about how a robbery-murder was discovered in one of the
plains states in the "Old West", late 1800's. The felon hid the loot by
burying it in a wagonload of grain he was driving to market, and was
caught by townspeople when coins and a pocketwatch "floated" to the top of
the grain after hours of jiggling and shaking on the crude roadway.

Best wishes,

Larry

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Larry Cartwright
Physics, Physical Science, Internet Teacher
Charlotte High School, 378 State Street, Charlotte MI 48813
<physics@scnc.cps.k12.mi.us> or <science@scnc.cps.k12.mi.us>

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

On Mon, 1 Feb 1999, Ludwik Kowalski wrote:

A strange observation. I put about 1/3 spoon of coffee (Taster's
Choice, 100% pure Instant) into a glazed porcelain (clay ?) cup.
Then about the same volume of Coffee Mate powder (non-dairy
creamer Carnation, a little package from Nestle).

Before adding hot water I started shaking the cup to mix two
powders. Brown coffee grains are larger than while "milk"
powder. NO MATTER HOW LONG I SHAKE I still do not see
uniformity. White powder particles like to stay together, more
or less. Two substances mix but not totally. After some shakings
the mixture becomes nearly uniform but a clear tendency for
clustering seems to prevail. Shaking seems to do two things:
mixing and separating big particles from small particles.

My white cup, by the way, has Einsein's face on one side and
E=m*c^2 on the other. I am sure this is purely coincidental. The
mean depth of my mixture is about 3 mm or so. The bottom
is not perfectly flat. An illusion of some kind? A wrong way of
mixing?
Ludwik Kowalski