HISTORY OF INORGANIC SALTS 151 



of work. Urea, ammonia, and kreatinin are increased, and 

 if the subject is in poor training the uric acid and purin bases 

 also. 



Carbon Equilibrium. The condition of carbon equilibrium 

 is of lesser importance and less easily attained than nitrogen 

 equilibrium. A normal adult of constant weight is in carbon 

 equilibrium, and when the quantity of non-nitrogenous food 

 is increased there is a greater tendency for it to be stored and 

 not so great a tendency toward its destruction. Carbon 

 equilibrium may be attained on an exclusively protein diet. 

 For a man of 70 kilos, the daily excretion of carbon on an 

 ordinary diet is 250 to 300 grams. About 2000 grams of lean 

 meat would be necessary to yield the same amount of carbon, 

 necessitating the destruction of three times the ordinary 

 quantity of protein in the short cut to urea through the liver. 

 Individuals differ greatly in the ease with which they store 

 carbon. Some, upon a relatively small diet, form much fat, and 

 others remain thin in spite of the ingestion of a very liberal 

 diet. The reason for the difference depends upon the capacity 

 of the body to destroy food material. Within limits this is 

 affected by the character of the daily life. Sedentary work 

 absence of worry, etc., tend to the accumulation of fat, while 

 a very muscular life has the opposite effect. Alcohol, long 

 continued, by sparing carbohydrates and fats and by depressing 

 the oxidative power of the body tends toward the accumula- 

 tion of fat. 



History of Inorganic Salts. These, in general, do not 

 undergo any decomposition in the body. An exception is 

 to be found in the chlorides, some of which are used in the 

 formation of the hydrochloric acid of the gastric juice. The 

 average amount of the inorganic constituents of the body, 

 determined as ash after incineration, is 4.3 to 4.4 per cent. 

 Five-sixths of this is derived from the bones. Muscle con- 

 tains from 0.6 to 0.8 per cent, of the moist weight. The more 

 important salts are the chlorides, phosphates, sulphates, 

 carbonates, fluorides, and silicates of potassium, sodium, cal- 

 cium, magnesium, and iron. Iodine is found in the thyroid 

 tissues. Potassium belongs, especially, to organized tissue 

 elements, while sodium belongs to the liquids more particularly. 

 Calcium carbonate and phosphate predominate in the bones. 



