DIFFERENT KINDS OF FOOD REQUIRED. The different periods and circumstances of life require their appropriate food, and the welfare of mankind demands that it should supply both the inorganic and organic substances employed in the development of every tissue. The inorganic elements employed in our construction, of which _Phosphorus, Sulphur, Soda, Iron, Lime,_ and _Potash_ are the most important, are not considered as aliments, but are found in the organic kingdom, variously arranged and combined with organic materials in sufficient quantities for ordinary purposes. When, however, from any cause, a lack of any of these occurs, so that their relative normal proportions are deranged, the system suffers, and restoration to a healthy condition can only be accomplished by supplying the deficiency; this may be done by selecting the article of food richest in the element which is wanting, or by introducing it as a medicine. It must be remembered that those substances which enter into the construction of the human fabric, are not promiscuously employed by nature, but that each and every one is destined to fulfill a definite indication. _Lime_ enters largely into the formation of bone, either as a _phosphate_ or a _carbonate_, and is required in much greater quantities in early life, while the bone is undergoing development, than afterwards. In childhood the bones are composed largely of animal matter, being pliable and easily moulded. For this reason the limbs of young children bend under the weight of their bodies, and unless care is taken they become bow-legged and distorted. Whenever there is a continued deficiency of the earthy constituents, disease of the bones ensues. Therefore, during childhood, and particularly during the period of dentition, or teething, the food should be nutritious and at the same time contain a due proportion of lime, which is preferable in the form of a phosphate. When it cannot be furnished by the food, it should be supplied artificially. Delayed, prolonged, and tedious dentition generally arises from a deficiency of lime. With the advance of age it accumulates, and the bone becomes hard, inelastic, and capable of supporting heavy weights. Farther on, as in old age, the animal matter of bone becomes diminished, and lime takes its place, so that the bones become brittle and are easily broken. Lime exists largely in hard water, and to a greater or less extent in milk, and in nearly all foods except those of an acid character. _Phosphorus_ exists in various combinations in different parts of the body, particularly in the brain and nervous system. Persons who perform a large amount of mental labor require more phosphorus than those engaged in other pursuits. It exists largely in the hulls of wheat, in fish, and in eggs. It should enter to a considerable extent into the diet of brain workers, and the bread consumed by them should be made of unbolted flour.