One of the things I bought with my Christmas present book tokens was a copy of ‘How to Fossilize Your Hamster’.  This has lots of experiments you can do at home, so instead of just reading it, I intend to work through it.  The first experiment is very interesting:

1) Get a wide-bottomed glass; the kind of flat glass you put cocktails in is fine (not the Martini one, the flat rounded one).
2) Pour 1 cm of Tia Maria in it. (It must be Tia Maria)
3) Very carefully pour a very thin layer of single cream (it must be single cream)  over a spoon, to float on top of the Tia Maria (a 2 mm layer is the sort of effect).
4) Watch the top of the drink.

The cream will break up into swirling cells, as it reacts with the Tia Maria.  It’s very pretty.

5)  This is because the alcohol dissolving in the cream reduces its surface tension, so it pulls in on itself.  The Tia Maria comes up to fill the spaces, but that has an even lower surface tension, so pulls in on itself.  A self-sustaining convection cycle is created.

(6) Drink the Tia Maria)

Now I have to look up the scientific research paper to match Physcia A 314 291.

(bet you didn’t know Science could be this much fun?)