In a properly balanced dietary there is not the slightest necessity for the addition of any mineral salts to our diet, and except for the almost universal presence of the salt-cellar on our tables we might remain in complete ignorance of their existence. Nevertheless, they are quite indispensable to the vital activities of the body, and animals from whose diet they have been purposely excluded quickly succumb. It is even of greater interest to know that the addition of inorganic mineral salts in correct proportions to a diet which has been exhausted of them is not sufficient to enable it to impart nourishing properties to the body. Mineral salts in the food must therefore exist in some organised form or vital association, and their deprivation even in small quantities is frequently followed by disease. It is now known, for example, that the peculiar malady so prevalent in the East and known as beri-beri owes its inception to the use of polished rice as the staple article of diet, and the addition of the external coats which have been "polished" off the rice soon exterminates the disease. The lacking essential ingredient which is responsible for the outbreak of this disease is some organic compound of phosphorus, and it is worthy of being noted that while the addition of inorganic or even organic phosphates cannot stay the malady, substances like peas or beans, yeast, wheat bran, or rice meal, all of which contain this organic phosphorus in large proportions, at once cure the disease when present, or prevent its development.

On a mixed diet containing a fair quantity of animal food there is really no necessity to add any common salt at table, because animal food already contains an abundance of mineral matter. Nevertheless, most people consume more than half an ounce per day, and it is open to question whether in some cases it may not be extremely harmful to do so. In any case, those who are subject to catarrhal ailments of one kind or another, such as frequent colds in the head, would do well to keep their supplies of common salt within the most moderate limits. Despite this statement, there is no reason to believe that in the average case even a fairly large consumption of salt is attended with injurious results, and there is not the slightest evidence to show that it is in any way associated with the production of cancer, as has sometimes been asserted.

As the human body contains altogether about seven pounds of mineral matter, most of which is to be found in the bones, one is rather surprised to find that we only require about two-thirds of an ounce of mineral matter daily, and apart from the addition of salt which is probably superfluous, the ordinary daily mixed diet is capable of supplying more than this quantity. Sodium, potassium, calcium, magnesium, iron, phosphorus, sulphur, chlorine, are the most essential mineral constituents of the food. Sodium is found chiefly in animal foods, potassium chiefly in vegetable foods - potatoes being especially rich in it; calcium (lime) is especially abundant in milk, eggs, rice, asparagus, and magnesium usually goes hand and hand with it; iron exists in fairly large proportions in spinach, yolk of egg, beef, apples; whilst phosphorus and sulphur are common in most protem-containing foods, cheese, haricot beans, and mutton being notable for the quantity they contain.