Hand Boiler, Glass Love Meter (colors and shapes vary) Educational Toy

• They come in 16 different styles and colors.
• Try this with several of your friends.
• Whoever makes the liquid rise and reach bubbly boiling point most quickly, wins!
• That person is obviously the hottest, most romantic and loving member of the party!
• These are made of glass and safe liquid.

It is a pretty fascinating science toy and an excellent demonstration of energy transfer. 

Hand Boilers come in several different colors including: blue, green, yellow, purple and red and several different loop shapes.  

Hand boilers demonstrate Charles's Law and vapor-liquid equilibrium. 

The colored liquid in the boiler is comprised of a volatile mixture of liquids that have a boiling point just above room temperature.  The body heat from your hand causes the liquid to boil, which in turn makes the liquid evaporate, turning it to gas. The expanding gas pushes the liquid upwards and when you release your hand, equilibrium is re-established. The gas condenses into a liquid again and flows back into the lower bulb.