Yes; the higher the balloon ascends, the lower the quicksilver in the barometer sinks.

When we descend into the mines dug in the earth, does the air become heavier?

It does; and the quicksilver in the barometer rises.

At what temperature does water boil?

Water boils at a temperature of two hundred and twelve degrees.

When the weight of the air is taken off, will the water boil at a lower temperature?

Water will then boil at a lower temperature.

Where will water boil at the lowest temperature, on a mountain, or in a valley?

It will boil at the lowest temperature on a mountain.

At how much lower temperature will water boil, as we ascend?