THE CHEMICAL COMPOSITION OF THE BODY. 127 



is about 44 Ibs. ; while an uncertain quantity (perhaps i to f Ib.) is 

 formed by chemical action within it. (Dalton.) 



The loss of water from the body is intimately connected with excre- 

 tion from the lungs, skin, and kidneys, and, to a less extent, from the 

 alimentary canal. The loss from these various organs may be thus ap- 

 portioned (quoted by Dalton from, various observers). 



From the Alimentary canal (faeces) . . . . . ",' * 4 per cent. 



Lungs . . . t .20 



" Skin (perspiration) . . 30 " 



" Kidneys (urine) . ....... 46 " 



100 



Sodium and Potassium Chlorides are present in nearly all parts of the 

 body. The former seems to be especially necessary, judging from the 

 instinctive craving for it on the part of animals in whose food it is defi- 

 cient, and from the diseased condition which is consequent on its with- 

 drawal. In the blood, the quantity of sodium chloride is greater than 

 that of all its other saline ingredients taken together. In the muscles, 

 on the other hand, the quantity of sodium chloride is less than that of the 

 chloride of potassium. 



Calcium Fluoride, in minute amount, is present in the bones and teeth, 

 and traces have been found in the blood and some other fluids. 



Calcium, Potassium, Sodium, and Magnesium Phosphates are found in 

 nearly every tissue and fluid. In some tissues the bones and teeth the 

 phosphate of calcium exists in very large amount and is the principal 

 source of that hardness of texture on which the proper performance of 

 their functions so much depends. The phosphate of calcium is intimately 

 incorporated with the organic basis or matrix, but it can be removed by 

 acids without destroying the general shape. of the bone; and, after the 

 removal of its inorganic salts, a bone is left soft, tough, and flexible. 



Potassium and sodium phosphates with the carbonates, maintain the 

 alkalinity of the blood. 



Calcium Carbonate occurs in bones and teeth, but in much smaller 

 quantity than the phosphate. It is found also in some other parts. The 

 small concretions of the internal ear (otoliths) are composed of crystalline 

 calcium carbonate, and form the only example of inorganic crystalline 

 matter existing as such in the body. 



Potassium and Sodium Carbonates are found in the blood, and some 

 other fluids and tissues. 



Potassium, Sodium, and Calcium Sulphates are met with in small 

 amount in most of the solids and fluids. 



Silicon. A very minute quantity of silica exists in the urine, and in 

 the blood. Traces of it have been found also in bones, hair, and some 

 other parts. 



