Oil and Water Experiment Question

[FlashFry]

Hey everybody, I am currently in the process of coming up with a neat experiment for my thermodynamics class and I ran into some trouble. In my thermo class we were discuss phases, and separations and such, and I thought it would be cool to show how ice is less dense than oil and will float, but as it melts into water it will sink through an oil medium.

I am so far successful in recreating the melting part, however, I wanted to add something to this. I wanted to have the water droplet at the bottom of the oil medium refreeze and rise to the top (sort of like a reverse lava lamp).

My design is something like a foot tall glass cylinder, filled with vegetable oil. I let some ice float of on top and slowly melt. At the bottom of the cylinder, I have it sitting in an ice bath with salted water (attempting to get the temp < 0c). Unfortunately it is not working...

After doing some research I learned there can be issues with the water surface tension and sticking to the glass. I've also been having trouble getting the bottom of the glass cold enough to refreeze the droplets. I am hoping to get this to be a continuous process to show off to my class. After some brainstorming I was thinking of including another medium between the oil and glass to allow the water to sit without sticking, I might using dish soap... As for the freezing, I was thinking dry ice.

Any help or other ideas for showing off these cool thermodynamic principle would be greatly appreciated, thank you for your time!

 

[Curl]

Dish soap is soluble in water so I don't think it would work. Dry ice *might* work, you have to tie it to a rock and drop it in, but the bubbles could give you trouble.

My recommendation is to put the entire thing in a freezer and capture it on video, then bring a flash drive to class with the file and play it over a projector if you have one available.