Sandra Campbell, age 12, of Camden, N.J., for her question:

HOW DO YOU MAKE VINEGAR?

Vinegar is a sour liquid that is often used on salads. The liquid is also used in pickling and processing some fruits, vegetables and meats.

Vinegar comes about as a result of a chemical change known as fermentation. A weak alcohol, called a dilute, is the raw material from which all vinegar is made. The alcohol can be produced from the fermentation of the juice of any fruits, berries or melons.

Sugar solutions made from molasses, sugary syrup or honey can also be used to make vinegar. Cereals are used to make malt vinegar.

A slow, natural process or a quick process can be used in making vinegar. The slow process may take from one to two years, depending on temperature and access to air. The fermented liquid may be kept in oak barrels, or casks, with holes to permit air circulation.

In the quick method, the fermented cider or other liquid is circulated continuously through vats called generators. The generators are filled with such porous materials as corncobs, rattan shavings or coke.

Lukewarm, strong cider vinegar is circulated through the porous material for from 24 to 72 hours. Then it is fed into the top of a generator through revolving spray. The cider is split into drops and each drop is brought into contact with currents of air that enter through holes near the bottom of the generator.

An efficiently run generator converts 1,000 to 2,000 gallons of cider into vinegar in 48 to 72 hours.

During the process of converting fermented fruit juices into vinegar, particularly cider vinegar, a slimy scum called mother of vinegar forms. Manufacturers try to prevent the formation of vinegar mother. It slows down the circulation of air.

In the slow process of making vinegar, the fermented liquid is put in barrels that are only four fifths filled to allow ample air space.

The English word "vinegar" is from the French word "vinaigre," which means "sour wine."

As the alcohol comes in contact with the air during the slow process of making vinegar, acetic acid is formed. The top layer of liquid then increases in weight and gradually sinks to the bottom of the barrel. This continues until almost all of the alcohol becomes vinegar.

The odors, colors and flavors of various kinds of vinegar come about from the substance from which the vinegars are made.

Cider vinegar has an apple like odor and is yellow or brown. Distilled vinegar, on the other hand, has no color or flavor other than acidity.

Most distilled vinegars are made from molasses.