A hand boiler is a scientific toy, made from hand blow glass and filled with a ethyl alcohol.

The boiler consists of a larger lower bulb and smaller upper bulb, connected together by a twisting glass tube.

Hold the lower bulb in your hand and as the liquid is warmed, the pressure in the lower bulb increases and pushes the liquid through the loops to the upper chamber. When all the liquid is pushed out of the lower bulb, expanding air will bubble through the tubing making it appear that the liquid is boiling.

It functions similar as the drinking bird.