Hands Down, an Edmund Classic! — Hand Boilers are looped and twisted glass sculptures containing a liquid that will “boil” as heat is transferred from your bare hand. Simply hold the large bulb end in the palm of your hand and within minutes, your body heat will cause the liquid to rise. – Once out of your hands, it takes a few minutes for the liquid to cool down and return to the large bulb. Pretty fascinating science and an excellent demonstration of energy transfer. Comes in four different colors: red, blue, green and purple.
How does it work?: The heat from your hand appears to make the liquid boil. This is a result of Charles' law by Jacques Charles, who in 1787 discovered that a gas' volume is proportional to its absolute temperature. At a constant pressure (inside the glass), the gas' volume increases as the temperature increases. This means the heat from your hand causes the gas inside the glass to expand enough to displace the liquid.
Caution Part I: FLAMMABLE! Contains Ethyl Alcohol. Do not use near heat or flames. Avoid contact with eyes. In case of Eye Contact, flush thoroughly with water. If irritation persists, get medical attention.
Caution Part II: GLASS! This item is not a toy and is not intended for children. Use by children should be under direct adult supervision!