=Moldy cheese.= In the case of the cheddar cheese and other types of hard cheese, it is essential that their surfaces be kept clean, and not discolored by the growth of molds, which find favorable conditions for growth on the surface of the cheese in the moist atmosphere of the curing room. The molding of cheddar cheese can be prevented by covering the cheese with a layer of paraffin which stops the development of the mold spores, by shutting off the necessary supply of oxygen. For this purpose the cheese are dipped in melted paraffin when a few days old. In the case of types of cheese which are salted by applying the salt to the surface, or with soft cheese which ripen from the outside, other methods of mold prevention are employed, such as rubbing and washing the cheese. The curing room itself may be freed from the mold spores by the use of such standard disinfectants as formalin or sulphur. =Swiss cheese.= One of the most important kinds of hard cheese, is the Swiss or Emmenthaler, so named, from the country and valley in which the cheese was first made. In America, this type was introduced by Swiss immigrants, and is being made in constantly increasing quantities in Ohio and Wisconsin. Swiss cheese is a hard firm type, appearing in the markets in the form of the flat circular "drum" cheese, two to three feet in diameter, and six to eight inches thick, or in the smaller "block" form. In this country the cheese is prepared twice a day, since it is necessary to work up the milk while it is perfectly sweet. Indeed, the milk is received at the factories while it is still warm, and within five or six hours after it is drawn from the cow the cheese is on the press. If the attempt is made to prepare Swiss cheese from the kind of milk that is best suited for cheddar purposes, _i.e._, milk in which the acidity has increased to some extent, the flavor of the resulting product is likely to approximate a cheddar cheese rather than that of a Swiss. In the salting process, the salt is not mixed with the curd before it is pressed, but is applied by immersing the cheese for a few days in a saturated brine, and then rubbing salt over the surface of the cheese. In this way the salt gradually diffuses quite uniformly through the cheese. The method of salting has apparently a marked influence on the ripening process, since if the salt is added in the same way, and in amounts used in the cheddar process, the flavor will not be that of a Swiss cheese but will resemble a cheddar.