If beef tea, which so soon becomes distasteful to the sick, is flavored with different savory or aromatic substances, as parsley, sage, or mint, it is taken with greater relish. _Mustard_, so commonly used with cold ham or other meat and in salad dressing, is sometimes of benefit in stimulating the appetite, but when used in large quantities, or continuously, it may irritate the stomach. This irritant quality may be used to advantage, when it is deemed necessary, as a counter-irritant on the skin, as in the well-known mustard plaster. A teaspoonful of mustard to a pint of lukewarm water is an effectual emetic in cases in which it is necessary or advisable to empty the stomach. _Capers_, the flower buds of a bush grown in the East, are put up in vinegar and used in sauces for mutton. _Cinnamon_, _nutmeg_, and _cloves_ are useful in flavoring foods; they take the flat taste from hot water and impart a pleasant spiciness. Many can take milk when flavored, and the slight amount necessary is in no way injurious. _Preserved ginger_ is of value for flavoring cereal foods and gruels for invalids. _Vinegar_, used in excess, reduces the alkalinity of the blood and aids in the destruction of red blood corpuscles. It may thus produce anemia when used in excess. The acetic acid contained in _cider vinegar_ aids the softening of the muscle fiber of meat and thus facilitates its digestion. Because of its preservative qualities it is used in pickling vegetables and various kinds of fish. Vinegars made from grapes or other fruits are wholesome. Flavored vinegars, as tarragon, from the herb of the same name, are useful as appetizers. Vinegars artificially made from commercial acids are sometimes injurious. _Tomato Catsup_, _Worcestershire_, and _Tabasco sauces_ are not harmful if used moderately and with due regard to enhancing not destroying the flavor of the food with which they are used. _PRESERVATION OF FOODS_ This subject is of ever-growing importance. The study of the preservation of foods has added much to the store of human knowledge. By this means it is possible for those living in districts remote from the supply, those who cannot afford to buy them fresh, and those who have no cellars in which to store them, to have vegetables and fruits at all seasons of the year. Nutritious foods can be prepared in such small bulk and of such excellent keeping quality that explorers, whether to the arctics or the tropics, can be kept in first-class physical condition, enabled to withstand fatigue, and be removed to long distances from the base of supplies without great hardship. The decomposition of food is occasioned by bacterial action. Air is necessary to the growth of bacteria. If the air is excluded the ordinary bacteria are prevented from exerting their deleterious action. Heat, as in canning, prevents the formation of bacterial products. Cold, in refrigeration, by inhibiting bacterial activity is also an excellent preservative.