点燃底部酒精灯（furnace），烧煮圆底烧瓶（boiler）中的水，

Ignite the furnace at the bottom and boil the water in the round-bottomed flask. The water turns into water vapor when heated. Then, as the water vapor pressure in the round-bottomed flask increases, the water is squeezed into the upper container through the pipe. In the cup with coffee; when the heat source is removed, there is no obvious change at first, and then the coffee liquid from the top drops down the tube. Because there is residual heat on the wall of the bottle when the heating is stopped, the pressure in the bottle decreases after the water vapor decreases, and the remaining pressure cannot support the quality of the coffee liquid in the upper cup, so the coffee liquid will fall.

Ignite the bottom alcohol lamp (furnace), boil the water in the round bottom burner (boiler), the water heat into water vapor, and then as the water vapor pressure in the round bottom burner becomes greater, and then the water is squeezed through the pipe into the cup containing coffee above; Due to the stop heating moment bottle wall residual heat, to cool the water vapor to reduce the pressure in the bottle reduced, the remaining pressure can not support the quality of coffee liquid in the cup above, so the coffee liquid will fall.

Ignite the alcohol lamp at the bottom to boil the water in the circular bottom flask. The water changes into steam when heated. Then, as the water vapor pressure increases in the round bottom flask, the water is squeezed into the cup containing coffee through the pipe. When the heat source is removed, there is no obvious change at first, and then the coffee drops down the pipe. When the heating is stopped, there is residual heat on the wall of the bottle. After cooling, the water vapor decreases and the pressure in the bottle decreases. The residual pressure cannot support the quality of the coffee liquid in the upper cup, so the coffee liquid will fall.<br>