15, Surface tension

Divination

Divination is an incredibly difficult skill to master. It's made a little easier when there are a number of skilled magicians working together.

In the movies people often do divination by gazing into clear water. What a load of rot. You can't see anything in water. No, for a divination you need good fresh milk. Giant sloth milk is prefered, but cow milk will do at a pinch.

If you want to get an idea of how divination works, put some milk in a dinner plate or pasta bowl, just a few mm deep. Grind pepper on top so it covers the surface of the milk. Now touch the tip of your finger to some washing detergent and lightly touch it to the centre of the bowl. See what happens!

This is a great experiment for parties, simple to do and, with a little sleight of hand, appears Magic.

What you need

• A bowl
• Ground pepper
• Dishwashing liquid
• Milk (or water if you must)

Activity

Fill the bowl with milk.

Toss some ground pepper across the water's surface. Make sure it’s a reasonable amount.

Add a drop or two of dishwashing liquid and watch what happens. You don’t need a lot, but you should experiment with different amounts.

Making it magic

This is science but add some theatre and it becomes magic.

Imagine, gathering all your friends around you and in a mysterious voice saying

“Now ladies and gentlemen, we’re going to perform a divination. I’m going to take this bowl of clouded water, and, using the power of my mind, clear a path to what has been and what will come.”

As the pepper ring forms at the edge of the bowl you can make up all sorts of stories about the future to entertain your friends.

What’s happening?

Why does the pepper race away from the soap? This happens because the dishwashing liquid breaks the water's surface tension, allowing the water to pull the pepper away from your finger. Amazing isn't it?

The surface tension of the water creates a slight upwards bulge across the water’s surface. When the surface tension is broken, the top molecules, race away from the centre as the bulge collapses, carrying the pepper with them.

You can see a great explanation here