Once upon at time there was a certain smell that floated up from the kitchen as your small child's feet reluctantly met the cold floor. You dressed quickly, propelled by the promise of a warm woodstove and the aroma of warm biscuits. Biscuits, slathered with gravy or thick slabs of butter or drenched with preserves made from the berries you picked yourself. Biscuits, as American as Mom, the flag and apple pie.

Biscuits are an authentic slice of Americana not just because of their nostalgic associations with our nation's rural past but also because their essential ingredient -- baking powder -- is a distinctly American invention.

Now it's a household item, a staple on every baker's shelf, the substance without which quick breads and cakes would be flat as the proverbial pancake. Chemically, baking powder is a mixture of a carbonate (baking soda), an acid (cream of tartar, calcium acid phosphate or sodium aluminum sulphite) and a starch (cornstarch). When moistened, the carbonate and acid react to liberate carbon dioxide, producing inert bubbles which when heated cause the dough to rise quickly.

Prior to the production of baking powder in the 19th century, it sometimes took as long as five hours to beat enough air into cake recipes. Up to 15 eggs might be used in one cake. Otherwise, the leavening of baked goods depended on yeast, sour milk, baking soda or the sometimes painful beating of egg whites. In Maryland biscuits were customarily beaten, a process requiring hours of pounding with a mallet until the dough cracked.

In Colonial America housewives used pearlash (potassium carbonate) with molasses in gingerbread. Saleratus (bicarbonate of soda), an early form of baking powder, quickly followed. Lumps of alum (sodium aluminum phosphate) dissolved in sour milk or lemon juice were often added to this substance. Soon word spread to the Colonies that cream of tartar, imported from Italy and therefore terribly expensive, combined with baking soda could simplify the baking process and also could be added to egg whites before beating.

In the 1860s two Indiana druggists perfected a combination of cream of tartar and cornstarch and labeled it Royal baking powder. In 1875 E. N. Horsford, a Harvard professor of chemistry, developed a less expensive phosphate baking powder which he sold as "Horsford's bread preparation," later called Rumford baking powder. Next came Calumet, concocted by two salesmen in a Chicago attic.

For the next 50 years, the baking powder controversy dominated trade advertising. Manufacturers of the more expensive cream of tartar brands claimed that alum was a poison gas, caused indigestion, shriveled the stomach and made women nervous. One cartoon showed a pan of old bones with a caption explaining that phosphate baking powder was made from old bones treated with oil of vitriol. An item in a Pennsylvania paper headlined the poisoning of an entire family from a cake made with baking powder. Sales plummeted, though subsequent, calmer investigators determined that the poisoning's cause was not baking powder but sausage made from a newly painted sausage machine. By 1927 the Federal Trade Commission had enough evidence to declare baking powder in its alum, tartaric acid and phosphate forms equally acceptable for the American consumer.

The following baking powder recipe produces biscuits in less than 10 minutes: BAKING POWDER BISCUITS Makes about one dozen 2 cups sifted all-purpose flour 1/2 teaspoon salt 3 teaspoons baking powder 5 tablespoons butter or shortening 3/4 cup cold milk 1 hissing hot cookie sheet

Sift together the flour, salt and baking powder; cut or work in the butter until thoroughly blended with the flour. Using a spatula, mix quickly to a soft dough with the milk. The less baking powder biscuits are handled the better. (This combination causes the first chemical reaction.)

Turn onto a well-floured board and roll out or pat the dough with your hands to about 1/2 inch thick. Cut into 2-inch diameter biscuits (for smaller biscuits raise oven to 475 degrees) and lay them, about one inch apart, on a hissing hot ungreased cookie sheet. If the biscuits are placed slightly apart in a hot pan, they'll be lighter and crispier.

For a brown crust brush over with milk before baking. For a tender crust brush over with melted butter. Quickly place them in a preheated 450 degree oven for 12-14 minutes.

Variations: Biscuits are easily altered to suit your breakfast, lunch or dinner needs. Sprinkle before baking with cinnamon and sugar or parmesan cheese. Or fold into the dough a few tablespoons of grated, dying cheese from your refrigerator, cooked crumbled bacon or chopped parsley, basil or dill. For shortcake add 1 tablespoon sugar to the dough, flatten to 1/4 inch thick and proceed as above. HOMEMADE BAKING POWDER Makes 4 cups 1 cup cream of tartar 1 1/2 cups baking soda 1 1/2 cups potato flour or cornstarch

Sift the above mixture and cover securely in a dry can.