THICKENING SOUP.--Although thin, clear soups are preferred by some and are particularly desirable for their stimulating effect, thick soups find much favor when they are used to form a substantial part of a meal. Besides giving consistency to soup, thickening usually improves the flavor, but its chief purpose is to give nutritive value to this food. In fact, whenever a soup is thickened, its food value is increased by the ingredient thus added. For this reason, it is advisable to thicken soups when they are desired for any other purpose than their stimulating effect.

The substance used to thicken soups may be either a starchy material or food or a puree of some food. The starchy materials generally used for this purpose are plain flour, browned flour, corn starch, and arrowroot flour. Any one of these should be moistened with enough cold water to make a mixture that will pour easily, and then added to the hot liquid while the soup is stirred constantly to prevent the formation of lumps. A sufficient amount of this thickening material should be used to make a soup of the consistency of heavy cream.

The starchy foods that are used for thickening include rice, barley, oatmeal, noodles, tapioca, sago, and macaroni. Many unusual and fancy forms of macaroni can be secured, or the plain varieties of Italian pastes may be broken into small pieces and cooked with the soup. When any of these foods are used, they should be added long enough before the soup is removed to be cooked thoroughly.

Purees of beans, peas, lentils, potatoes, and other vegetables are especially desirable for the thickening of soups, for they not only give consistency, but add nutritive value and flavor as well. Another excellent thickening may be obtained by beating raw eggs and then adding them carefully to the soup just before it is to be served. After eggs have been added for thickening, the soup should not be allowed to boil, as it is liable to curdle.

KEEPING STOCK.--Soup stock, like many other foods, spoils quite readily. Therefore, in order to keep it for at least a few days, it must receive proper attention. At all times, the vessel containing stock should be tightly closed and, especially in warm weather, the stock should be kept as cold as possible. Stock that is heavy enough to solidify into a jellylike consistency when it is cold will keep better than stock that remains liquid. The addition of salt or any spicy flavoring also helps to keep stock from deteriorating, because these materials act as preservatives and prevent the action of bacteria that cause spoiling. Bacteria may be kept from entering soup if, instead of removing the grease, it is allowed to form in a solid cake over the top. No matter which of these precautions is taken to prevent stock from spoiling, it should be heated to boiling point once a day when it is to be kept for several days.