This section is from the book "Mrs. Allen's Cook Book", by Mrs. Ida C. Bailey Allen. See also: The Conscious Cook: Delicious Meatless Recipes That Will Change the Way You Eat.
To clear soup stock, add to each quart of stock the crushed shells of three eggs; mix thoroughly and heat to boiling point, stirring all the time. As the liquid becomes heated the egg coagulates and collects the fine particles floating in the stock. Let it boil vigorously for five minutes, add a little cold water, as for coffee, let it cool slightly, skim and strain through a cheesecloth spread over a colander.
To this soup stock various vegetables may be added, such as carrots, turnips cut in narrow strips, whole string beans, canned peas, chopped cabbage, small sections of cauliflower, etc., or it may contain rice, barley or tapioca, any one of which may be cooked in the liquor, thickening it slightly. However, when many vegetables or much cereal is added, the soup ceases to be merely an accessory, and becomes a food, although at the same time it does not 'lose its stimulating qualities.