Strong bottles, jugs, and jars, if they can be securely stoppered, may be used sometimes instead of hot water bags. The same precautions are necessary. Bricks, flat irons, or thick flannel bags containing salt or sand may be heated in the oven and used in the same way. Salt and sand retain heat for a long time, but are correspondingly slow to heat; therefore one bag should be heating in the oven while the other is in use. Their effect on the skin must be no less carefully watched than the effects of other hot applications. Hot dry flannel may be used without fear of burning a patient, and it sometimes yields sufficient warmth to relieve pain, particularly abdominal pain of babies. After it has been heated on a radiator or in an oven, it should be applied quickly and covered closely with another flannel to prevent escape of heat. Dry heat can be applied conveniently by an electric pad. The part to be heated may be wrapped in flannel or placed directly above or below the pad. The pad should be carefully watched to see that the switch is not accidentally turned, as it is possible for the pad to become hot enough to burn the patient or to set fire to the bed covers. MOIST HEAT.--To apply moist heat poultices or fomentations (stupes) are used. _Poultices_ may be made of various heat-retaining substances, but flaxseed meal is generally used. The poultices when ready should be applied without delay, therefore all preparations should be made in advance. To prepare a poultice, first provide a piece of gauze or thin old muslin about two inches wider than you wish the poultice to be when finished, and about two inches more than twice as long. In a shallow saucepan boil water, varying in amount according to the size of the poultice desired; about equal parts of water and meal will be needed. When the water is boiling briskly add the meal gradually, beating constantly with a spatula or knife. The poultice is done when the mixture coheres and is thick enough to drop from the spatula leaving it clean. Quickly spread a layer of the hot flaxseed from a quarter to half an inch thick on one-half of the muslin, leaving a margin on three sides of about an inch (Fig. 25). Fold in the margins of the cloth (Fig. 26) and then bring the other half of the cloth over the flaxseed so that the top of the poultice is covered. Tuck the free end of the upper half of the cloth under the turned in edges of the long sides. [Illustration: FIG. 25.--Turn the edges of the muslin over the flaxseed by folding first on the line _AA'_, and then on the lines _BB'_ and _CC'_.] [Illustration: FIG. 26.--Fold on the line _EE'_, bringing _FF'_ up over the flaxseed and tucking it under at _D_ and _D'_.]