URGENT

I need a material which is permeable to water, but impermeable to
glycerol (both chemicals are in liquid form).  (I strongly emphasize
that the material should be 100% impermeable to glycerol, or 99% at
worst.)

I'm not sure, but I believe that a "dialysis tube" can act as a
membrane which would satisfy the above criterion.

I require this material quickly so that I may continue with my project.  

So, two questions:  What material works, and, from which store may I
buy the material from?  (I live in Toronto.)

I'm hoping I can buy this material by Tuesday, May 25, 2004, so I can
continue with my project.

If I can buy it buy before or on the date above, and if the material
performs its function properly, then I will give a $5 tip.

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Clarification of Question by blochee-ga on 23 May 2004 21:32 PDT

made a mistake.  (I'll keep it brief this time.)

I need a material and a chemical which satisfy the following conditions:

1) the chemical is a liquid
2) the chemical should be insoluble in water
3) the chemical is non-toxic
4) the material is water permeable, but impermeable to the chemical

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Clarification of Question by blochee-ga on 23 May 2004 21:53 PDT

and add the following to the list:

5) the chemical is more dense than water