In any of these conditions the minimum of albuminous food, taken daily, should certainly be 100 grammes. But other persons can often manage with less without any wasting of the body proteids, so long as carbohydrates and fats are taken simultaneously in sufficient quantities. Besides the three principal groups of food there are certain other kinds which are almost as indispensable, e.g., mineral matter and water, without which no animal or man could live, and vegetable acids and cellulose. The most important mineral matters are lime salts, mainly in the form of phosphates. They are present in greatest amounts in cows’ milk. Common salt is a most important element of food, for which animals and men often risk their life. As Bunge shows, where vegetables that contain much potassium are taken, then common salt must be taken as well. He has shown by experiment upon himself, that when potassium salts are taken a great quantity of sodium chloride is eliminated from the body. The reason is, that when a potassium salt is taken, e.g., carbonate of potassium, and this, in the blood, meets with chloride of sodium, then chloride of potassium and carbonate of sodium are formed. But the kidney’s duty is to see that the composition of the blood is maintained, and that foreign substances, or the surplus of a normal substance like carbonate of sodium, are eliminated. Hence the carbonate of sodium and the chloride of potassium are together eliminated, and thus our blood loses two important elements: chlorine and sodium. Thus, when potassium is taken, the body loses sodium chloride, and then more of this substance is required. A diet of potatoes necessitates much salt, as they are rich in potassium; on the other hand, rice contains only minimal quantities of potash. Potatoes contain 42 grammes of potassium in 100 grammes; rice only 1 gramme. Thus rice as food would require only the smallest amount of salt. At the same time Bunge points out the great dangers to the kidneys of a diet from which quantities of an alkali salt are formed and circulate through these organs. We can draw a practical conclusion of great value from Bunge’s observations, and not use much salt in our food, nor too large quantities of vegetables containing much potassium, if we want to save our kidneys from harm. That salt is deleterious to the kidneys, especially when previously damaged, is shown by the works of Achard and Loeper,[259] Strauss,[260] Vidal and Javal,[261] and others. We have enlarged upon this in our chapters on the functions of the kidneys and their hygiene. Footnote 259: Achard and Loeper: C. R. Soc. biologie, 23 Mars, 1901. Footnote 260: Strauss: Die chronischen Nierenentzundungen, Berlin, 1902. Footnote 261: Vidal et Javal: Soc. Méd. des Hôpitaux, 26 J., 1903; Vidal: “Le regime dechlorusé,” Liége Congrès de Méd., 1905.