Australia's Science Forum

Hi
One of the teachers here just showed me this cool thing. Glycerine and glass have the same refractive index. Soooo if you put a little beaker inside a big beaker then fill the beakers with glycerine the little beaker disappears. It may be old hat to all you clever folk out there but it was new to me so I thought I'd share.
Krysia

Thanks. I didn't know that either. If I can find enough glycerine I'm keen to try it.

We do this using baby oil. The glass doesn't completely disappear so it may not be as good as glycerine but easier to get large quantities of. I just pour back into the bottle and save for next time. The other part is to put a glass dropper into the oil and then suck some oil up into it, now you see it, now you can't!

cooking oil works well...and is cheaper ...and can be recycled

WOW this actually works!.I got all excited and inspired when I read this thread yesterday that I had to see for myself. Told my HOD about it and how easy it was so next week he's going to do it next week with the kids who are currently studying "Light and Sound".

Judith

We do it with a short test tube or vial inside a little beaker. That way I don't have to find bucket loads of glycerine.

Just did it and have set it up as a display. Thanks for the idea it is a great demo.

gosh that is a old one.