Question for Kolter

[Dave Against The Machine]

I have no reason for wanting to know this, just curious. And I thought you would probly know this.
I was shining a lazer pen into a glass of ice water, admiring how cool it looked lighting up the glass. Then I though about those things that my teacher called Ghost crystals. Those things when you drop em in water they disapear, due to something about, light traveling through them at the same speed as light travels through water, so you can't see em when they are in water. I can't recall what the actuall name for them are. What are those things called?

[Vorticus]

I don't know the technical name for those, but the reason they disappear is that the crystal has the same amount of light refraction as the water. If I recall correctly, it only works with distilled water.

[Rkolter]

You just want the name?

Vorticus gave you the answer - the index of refraction for the crystal is equal to the index of refraction for the water, and both are transparent and colorless.

There are several materials that can do this; call them what you want - I'm pretty sure though that 'ghost crystal' is a silly name, since outside of a watery environment, you should be able to see them just fine.

[Dave Against The Machine]

Interesting. Thanks for the info. Now that gives me something to ponder about for the rest of the night. Other than, why haven't I started on Mondays comic.

[Nyke]

Then there's glycerine, which has the same refraction angle as glass, and you can use to hide glass in glass.

[Gengar003]

For what it's worth, my physics teacher called 'em "Ghost Crystals," too.

A google search turns up this, though:

http://chemmovies.unl.edu/chemistry/bec ... BD021.html

And a site to order them from:

http://soilmoist.com/

Apparently they're used in gardening.