having a crystal growing on your windowsill can be good fun. With food coloring, you can make them any color you wish.
The problem is finding a suitable chemical. You may have seen copper sulfate and potasium permanganate in school. Both can be quite toxic and are therefore not easily available in a local drug store. Your science teacher may allow you to have a sample, it you ask very politely.
For this chapter, we decided to use potassium aluminum sulfate, better known as alum powder. It is a non-toxic substance that used to be used to whiten bread. As with any household substance, you shouldn't get it in your eyes. It is available from the following website: www.sciencecompany.com. It is also commonly sold as foot powder. 1 ounce will cost you about $3 at the time of writing, not including postage. That is enough for crystal making, but alum can be used for fireproofing and tanning skin- as discussed in other chapters. It also works as an astringent on small cuts, or the crystals can be used as an underarm deodorant. You might want to get more. Alternatively, you can grow crystals with common salt or sugar.
YOU WILL NEED:
- 10 grams of potassium aluminum sulfate (alum)
- a glass tumbler
- a popsicle stick
- warm water
-thread
- small stones, preferably with sharp edges (but be careful!!)
METHOD:
1. Make sure the stones are clean-wash them thoroughly in running water
2. Put enough warm water int he tumbler to cover the stones. (about a third of the cup). Do not put the stones in yet.
3. Add the alum and stir furiously with the stick until it stops dissolving easily. You may be left with a few grains at the bottom. Ignore them. You can either put the stones straight in or, for the classic look, tie a thread around a small stone and the other end around the stick, as in the pictures. We did both
4.If you are intending to add food coloring, do it now. Show proudly to parents, who will pat you on the head for being a "little genius".
Evaporation is the key for these small crystals, so make sure it is in a warm place. It will take a few days for the first ones to appear, and the full effect can take a few weeks. Larger crystals can be made by repeating the process- after tying a small crystal tothe thread.
The crystal you see here is a picture of the one we grew-the one on the left, not the enormous thing. The huge circle came from the bottom of the glass and in many ways is more impressive than than the actual crystal. It took about six weeks in total, and we refilled the alum once.
