Gary Kapenhaver, age 14, of Highland Park, New Jersey, for his question:

How does perfume keep its fragrance?

The petals of a lovely rose fade and fall all too fast and in a day or two its heavenly fragrance changes to a sickly odor. Most of the pleasant scents used to make elegant perfumes tend to fade or change their character in a short while. Nature's unpleasant odors seem to be built of sturdier stuff, for they tend to foul up the air long after the sweet scents have departed. The manufacturers of fine perfumes must have noticed this odd fact ages ago. Instead of feeling discouraged, they used the information to improve their products.

Skunks and many other animals have musk glands that produce foul smelling fatty oils. These fatty chemicals have a quality that enables them to keep their own smells and also other smells for a long time. The foul smelling ambergris produced in the stomach of the sperm whale also has this scent holding quality. The makers of costly perfumes purify oily animal musks and also ambergris. Small portions are added to the precious recipes to help the sweet scented ingredients to hold their fragrances for ages and ages