Show how air acts on mercury when the air around us becomes con into a smaller volume it becomes heavier puts greater arrs bure on the surface of the mercury and makes it ascend in the tube then the mercury lg said to rise when the clr expands swells into a larger volume it becomes lighter the pressure on the mercury Is jess the mercury sinks in the tube and the barometer la bald to fall therefore every change of height of the quicksilver which we observe Is a sign and measure of a change in the volume of air around vs |