I was digging around in an old bin of science supplies that that we had gotten from someone else when I found a small bag that contained what looked like large salt crystals. I stared at them for a minute pondering what they were.
Then I let out a loud maniacal laugh. Becki asked, “What is going on?” I replied, “Oh, I know what these are! They are ghost crystals.”
In my chemistry class, we called them “ghost crystals”. Really they are Potassium Polyacrylamide Crystals (about $13 on Amazon). They are super-absorbent crystals. They absorb so much water that when I dumped a small pile into a glass of water, they soaked up all of the water.
I guess I got carried away in my excitement.
So I dumped some out and added more water.
Check out our facebook page for a video of Elijah scooping up a bowl full of invisible crystals.
My favorite way to wow people is to tie a string around a crystal and lower it into the water. It looks like an empty loop, but then…
So why does this work?
The crystals absorb so much water that their index of refraction is almost the same as water. So when the light passes through the water and hits the crystal, it continues on as though nothing happened. So what you see is the same thing you would see if it was just a glass of water.
Check out the rest of the properties of light series here.