Hand boilers date back all the way to 1767 where Benjamin Franklin encountered them in Germany and promptly decided to make his own better version. They use the heat of your hand to expand the gas inside the cylinder pushing the liquid inside up or down. 

Hand boilers are great for:

• Teaching about pressure and how gas reacts to temperature
• Gifts for any science enthusiast
• Have contests with your friends about who can make the gas expand faster

Shipped in a 18x5x5 cm box