At the beginning there were only distilled water and powdery salts.

At first, the salt (in this case copper sulphate) has to be weighed out.

After that, the salt (in this case potassium-aluminium alum) is dissolved in water and heated.

We have it stirred! The rod creates a whirl in the copper sulphate solution.

This is not coffee, but potassium-chromium alum, which is stirred and

- filtered!

Our assistant, Verena, filtering the copper sulphate solution.

The glasses are covered and carefully labelled.

Three days later: There are crystals in the solution!

Now the crystals have to be retrieved from the solution!

The yield: Blue copper sulphate crystals and white potassium-aluminium alum crystals.

Our biggest specimen!