Lisa Pierson, age 13, of White Plains, N.Y., for her question:

WHERE DO WE GET LANOLIN?

Lanolin is a common name for wool wax. It is a greasy coating found on sheep's wool. The name is used especially to describe the wax when it is purified and mixed with water.

The lanolin we get from sheep's wool is a yellowish, sticky material that is as thick as ordinary wax. But it does not react readily with acids or alkalies.

Lanolin will absorb from 25 to 30 percent of its own mass in water. It breaks up easily into tiny droplets when mixed with water, which forms an emulsion known as hydrous lanolin, or lanolin USP. It is used widely in medicines such as salves and ointments, and also in cosmetics, because it is easily absorbed by the skin.

In addition, leather goods can be dressed with lanolin. And lanolin can also protectively coat metals, and be used as a base in grease paints and shoe polishes.