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 toy and an excellent demonstration of energy transfer. SKU:ADIB004WKHH1E