Stir the dry ingredients together. Stir egg whites, club soda, and parsley slightly with a fork and pour over the dry ingredients. Mix well and refrigerate at least one hour. Form into 8 balls (1 1/2 inch diameter) and drop into a large pot of boiling slated water or broth. Reduce the heat and simmer, covered, for 30 minutes. Do not remove the lid during the cooking period. Remove matza balls with a slotted spoon and serve in soup.