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Re: [rete] Passevin



For those who don't have red wine in the supply cabinet, you might try sugar water or salt water with food coloring. Your deparment head won't look at you quite as funny when you ask for a signature for sugar!

As a sort of reverse of this rapid change, you might try the opposite - put the heavier liquid at the bottom. I filled the bottom half of a graduated cylinder with blue sugar water, then carefully add red water on top. (I used a tube so that I could slowly add the water right at thr top of the lower layer without splashing, dropping, stirring, etc. I was greatly surprised that it took WEEKS for the colors to do much mixing. I also took apart a battery tester and added the little floating balls which floated in the purple region, slowly separating as the fluids mixed.

I can't remember now what inspired me to try this - if someone else had suggested it, or if it was a variation on some other demo I saw, or if it was just a random thought. Perhaps I should repeat the experiment and submit it to TPT in a short article.

Tim F


-----Original Message-----
From: Forum for Physics Educators on behalf of Brian Whatcott
Sent: Wed 6/23/2004 6:07 PM

A glass of red wine, full exactly up to the upper edge.
A second glass similarly full of water. A sheet of paper is put just on
the surface, in contact with the edge and with water.

Take the second glass in your right hand, maintain the paper sheet in
place with your left hand, and turn it over, while preventing the water
to flow outside the glass with the paper sheet. Put delicately the turned
over water glass on the first one, exactly edge against edge.

Then, very, very slowly, pull the paper sheet towards you in order to
remove it completely.

Then, very progressively, you see the diffusion of the red wine towards
the upper glass, while it is replaced by water in the lower one. After
some minutes, the upper glass is full of wine, and the lower is quite
clear ! It is really amazing.

P. Lauginie