Q. What is mortar?
A. Lime mixed with sand and water.
Q. What is lime?
A. Lime-stone burnt produces lime.
Q. Why is the lime-stone burnt, in order to make it into lime?
A. The fire expels the carbonic acid, and converts the hard lime-stone into a loose powder.
Q. Why does mortar become hard, after a few days?
A. Because the lime re-imbibes the carbonic acid of the air, which was expelled by fire; and the loose powder again becomes as hard as the original lime-stone.
Q. Why is mortar adhesive?