Question

Ever seen those hand boilers made of blown glass with liquid inside them? Ok, how do they work? (This is for a physics lab)

Answer 1

The key fact is that the liquid is trapped in the narrow tube between the reservoirs, and the tube projects below the level of the liquid in the reservoir below. When you warm the globe with your hand, the air above the reservoir expands according to Charles' Law. This pushes down on the surface of the reservoir and pushes the liquid up the tube into the upper reservoir. The liquid is not actually boiling, it's just the pressure of the trapped air that pushes it up. The bubbling happens when the reservoir is nearly empty and bubbles of air go up the tube. Gases have large coefficients of thermal expansion, which is why heating the air only a bit can push the liquid up the tube.

Answer 2

Thanks a lot!