Crystal formation

[c.labs4ever]

Hi All,
W are trying to compare fast and slow cooling of crystal for The changing Earth in year 8 and have used stearic & potassium nitrate but the differences are very hard to pick up.
Does anyone one have another chemical compound that works better in producing small crystals when cooled quickly and long crystals when cooled slowly?
Thank you
C

[AnnNos]

We use copper sulfate and get good results most of the time.

[rae]

Potassium nitrate is really good if you have it saturated and quite hot and then just turn the hotplate off underneath it and allow it to cool on the hot plate. Obviously the longer time it takes to cool the much bigger the crystals. I make sure my solution is super saturated.

[c.labs4ever]

Thanks guys