The Challenge
One shot glass contains water and the other contains whisky. The challenge is to make the liquids switch glasses without using another container.
What You’ll Need
🥃 Two Glasses
Use identical shot glasses with flat rims.
💳 Plastic Card
Use a rigid, waterproof card.
💧 Water
Fill one glass close to the rim.
🥃 Whisky
Fill the other glass close to the rim.
Fill Both Glasses
Fill one shot glass with water and the other with whisky.
Choose the Separator
Use a plastic gift card or another rigid, waterproof card.
Invert and Stack
Cover the water glass with the card, turn it upside down and align it over the whisky glass.
Create a Tiny Gap
Slide the card only slightly so the two liquids can meet without mixing immediately.
Wait for the Switch
The denser water slowly moves downward while the lighter whisky rises.
Why It Works
Water is denser than whisky. With a very small opening between the glasses, gravity allows the water to move downward while the lighter spirit rises.
Keep the gap tiny. A large opening causes the liquids to mix.
Video Demonstration
Performance Tips
Practise over a tray or sink first.
Keep the upper glass centred and steady.
Use conversation or a challenge presentation while the liquids switch.
🎩 Magic Tip
Present it as a puzzle and let spectators suggest solutions before revealing the slow exchange.
Common Mistakes
Do not make the opening too large.
Avoid absorbent or flexible cards.
Keep the glass rims aligned.
Practise the inversion before using filled glasses.
Frequently Asked Questions
Why do the liquids switch places?
Water is denser than whisky, so it moves downward while the lighter spirit rises.
Why must the gap be very small?
A tiny opening allows a gradual exchange. A large opening causes mixing.