Hi Victoria,

This looks like it fits your description:

Title: FIZZING SHERBET
Forum: rec.food.cooking
Date: 04/01/2000
Author: Miche

From the side of the King baking soda box...

Fizzing Sherbet powder is a very popular novelty for children. Lick it off a spoon, or off the end of a straw or licorice tube.

1 cup icing sugar (confectioner's or powdered sugar)
1 teaspoon baking soda
1 teaspoon citric acid
1 teaspoon tartaric acid
2 Tablespoons drink powder (a brand name was given; think Tang or Koolaid), any flavour

Grind citric and tartaric acid to a fine powder using a mortar and pestle or with the back of a spoon. Place all ingredients in a plastic bag and shake well to mix. Store in an airtight jar.

Happy Cooking,

Betsy
recipelink.com