Potassium Salts

Next in importance to sodium chloride ranks potassium chloride, which is the predominant salt of the muscles, and which, like sodium chloride, is a common ingredient of nearly all the tissues and fluids. The acid and neutral carbonates and phosphates of sodium and potassium are important in regulating the reaction of the digestive secretions and the urine.

Calcium

The salts of calcium are chiefly of value from their constituting a large percentage of the composition of the bones and teeth, as well as a smaller percentage of many other tissues of the body. Their presence seems to be associated constantly with cell growth and development. The carbonate is often found with the phosphate of lime, but in less quantity. The occurrence of cretinism and goitre has been in part attributed to an excess of lime salts in the food, more especially the drinking water; but this theory is not to be accepted without question. These diseases often occur independently of such cause, and are by no means always prevalent in lime-water areas.

Young growing animals contain a larger percentage of earthy salts than do older ones. Deposits of salts of lime occur in old abscesses, tubercular concretions, tartar on the teeth, atheromatous blood vessels, the arcus senilis of the cornea, and as calculi.

Phosphorus

Phosphorus is derived from phosphates in meat and its contained blood which is eaten, as well as from vegetables. It enters into the composition of the bones, muscles, blood, etc.

Sulphur

Sulphur is derived from sulphates contained principally in fibrin, egg albumen, the casein of milk, and from such vegetables as corn, turnips, cauliflower, and asparagus.

Iron

The iron of the body is found in the blood pigment, where it amounts, all told, to a third of an ounce. It is also present in minute traces in other pigments.

Its chief source is from the blood of animals which is cooked with their meat. Two quarts of milk furnish about one eleventh grain of iron. It is also derived from, and it may be taken with, chalybeate waters. Probably most of the iron of the body is retained and used again and again. The daily quantity of iron ingested with an ordinary mixed diet is about one eighth grain.

Vegetable Acids

The common organic or vegetable acids - citric, tartaric, malic, etc. - are derived from fresh vegetables and fruits, in which they exist usually in combination with the bases Ca, Na, K, etc. They are indispensable articles of food, for when absorbed they form carbonates, which aid in maintaining the alkalinity of the blood. Prolonged deprivation of them usually results in the condition of scurvy.