Q. I read recently that rhubarb was used at one time as a tonic with soda water for children. It was supposed to be a blood purifier. I have not been able to find a recipe for rhubarb soda. Do you have one?

A. The notion of substances functioning as blood purifiers satisfies the human yearning for health and long life. That's all it does. There is no tonic that purifies blood iust as there is no fountain of youth.

Herbal medicine as practiced today is based on 10 percent effective remedies, and 90 percent hocus-pocus. Notions that were widely held a thousand years ago are still repeated today. One foolish notion was that herbs and plants that resemble body parts were intended by some higher power to cure those parts. Rhubarb, whose stalks are bright red, resembles blood and would therefore be considered an appropriate blood remedy.

In addition, if there were such a thing as a blood-purifying tonic, rhubarb would be about the farthest from satisfying that need. The reason has to do with its content of oxalic acid, an organic acid with very low solubility. When absorbed through the intestinal wall into the blood, oxalic acid molecules form calcium oxalate salts, removing life-giving, soluble calcium from the body. In turn, the calcium oxalate precipitates inside the kidneys and eventually forms kidney stones.

Rhubarb leaves are very high in oxalic acid and for that reason are not consumed. The stems still contain some of the acid, though not nearly enough to pose a risk to health. However, if rhubarb was intended to purify blood, then it or its creator certainly took a step in the wrong direction.

Rhubarb nonetheless has a heady flavor and aroma much akin to that of apricot. It would make a delicious drink. Here's a recipe: RHUBARB NECTAR (Enough for 4 glasses)

1 cup rhubarb stem, cut in 1/2-inch sections

Grated zest of 1/2 orange

2 cups water

1 cup sugar or honey

1/8 teaspoon ground cloves

Simmer rhubarb and orange zest in water until rhubarb is tender. Add sweetener and cloves and bring back to boil. Pour into blender and blend until smooth. Chill and serve straight, or mix 1 part nectar to 2 parts soda water. A slice of lime makes an attractive, flavorful garnish.

For a rhubarb slush, blend 1 cup chilled nectar with 1 cup of crushed ice. Serve with a little stewed rhubarb or with slices of fresh strawberries.Q Do you have any tips on how to fill a pepper mill? Every time I pour peppercorns in the top, which has a narrow, shallow opening, they bounce merrily onto the counter, then onto the floor, converting the entire kitchen into a roller derby. A There's a simple, practical method to corral your peppercorns. Hold the pepper grinder in the left hand (your less capable hand, that is), encircling the top rim with the index finer and thumb. this creates a little funnel. Then, should you be just a little careless or shaky, they'll at least be contained. Tap the pepper grinder gently on the counter to make them drop down the hole.