What You Did
You grew a geode. You spent two days preparing a base on which rock crystals could grow, and then made observations on the third day. This is one of the longer experiments in the book.
On day three of this experiment, you should be able to see small crystals forming on the inside of your eggshell.
I did not saturate the water properly on my first test run of this experiment. So I added more alum powder until it wouldn’t dissolve any more, then removed the excess solids. I did get crystals to grow that way, but by that point, the powder that had been glued to the eggshell had completely dissolved, and instead of being attached to the shell, the crystals were floating in alum soup! That used up almost all of my alum powder, so I need to buy more for another try. Next time, I will make sure the water is fully saturated before I add the eggshell.My first test run also turned my food colors brown, though I used two drops of red and one drop of blue. I will try a different color next time, maybe yellow, to see what happens.If you didn't use enough alum powder, your crystals may not grow very large, or even at all in some cases.
Vary the length of time you soak your shell. Change the cooling rate of the solution
evaporation, solution concentration, crystal structure