The solids represented above are in the form of minute globules, and the serum in which they float is the water or “whey.” It is to unite these globules and separate them from the whey that is the primary function of cheese making. It so happens that rennet, the active agent in this process, besides exerting an automatic, chemical action on milk, imparts to the solids new and vigorous properties that give cheese a medicinal value to the human stomach, namely, an inceptor of digestion. It is imperative that a cheese maker understands enough about milk to instantly detect the slightest change from its sweet, pure, normal condition. Milk as a fluid is highly sensitive to unclean odors, and when it absorbs them in a greater or less degree, the maker should, by an olfactory test, discover the taint. Milk that has been tainted by a retention of the animal heat, not having been cooled when freshly drawn, will give off a rank, burned smell, nauseous in the extreme. If the taint was absorbed from odors, the peculiar scent of the particular stench will be indelibly impressed on the fluid. Mature or sour milk is more to be desired for cheese manufacture than milk poisoned by taint. In fact, a _slight_ maturity of milk is necessary—or, at least, desirable—to produce a fine cheese, the same as mature cream is required to develop good butter, only in the former the “ripeness” must be scarcely perceptible, while in the latter it must be well advanced. All tainted milk, and all milk that is “old” and nearly sour, should be unconditionally rejected at the cheese factory for manufacture. Do not be afraid of financially losing by such a rule. It is none too stringent, and in the end it will give your goods a trade reputation that will be secure and impregnable. The idea that really good cheese can be made out of poor milk is disproved by chemistry and common sense. SALT. One of the most important factors in cheese making is the saline mineral known as salt. A cheese can be manufactured gilt-edged in every way, but if it contains no salt, an insufficient quantity of it or that which is of weak, inferior quality, it is simply a mass of perishable, nitrogenous matter that will soon go to putrefaction. Salt checks the growth of the lactic acid as quickly as a rush of air snuffs out a candle; therefore, it has complete control over the quality of the cheese in this direction. It preserves that quality for an indefinite time, provided it exists in a sufficient proportion and the cheese has been scientifically made. Then, again, salt gives firmness and flavor to the cheese.