Tracy Torsberg, age 12, of Clayton, Wash., for his question:

HOW IS FORMALDEHYDE MADE?

A German chemist named August Wilhelm von Hoffmann discovered formaldehyde in 1867. The solution is used to preserve insects and other biological specimens and is also used for disinfecting, embalming and for making compounds such as urea resins and organic dyes. The plastic industry uses it combined with carbolic acid to make Bakelite, and it is also used to make fumigating candles.

Formaldehyde is prepared by oxidizing methanol, which is methyl alcohol, in the presence of catalysts. It is the simplest member of the aldehyde class of organic compounds. It is a colorless gas, easily soluble in water. It has a strong odor and can irritate the, eyes and nose.