IO4 THE CHEMICAL COMPOSITION OF THE BODY 



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 and Sulphates. These are found in 

 the blood and most of the secretions and tissues. 



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. 



Iron. The especial place of iron is in hemoglobin, the coloring- matter 

 of the blood, of which a full account will be given with the chemistry of the 

 blood. Iron is found, in very small quantities, in the ashes of bones, mus- 

 cles, and many tissues, and in lymph and chyle, albumin of serum, fibrin, 

 bile, milk, and other fluids. 



Iodine occurs as an iodized protein in the thyroid gland. Biologically, 

 it is found as a tri-iodotyrosin in sponges and the Gorgonian corals. 



Water. Water forms a large proportion, more than two-thirds, of 

 the weight of the whole body. Its relative amount in some of the principal 

 solids and fluids of the body is shown in the following table (from Robin 

 and Verdeil) : 



Quantity of Water in Per Cent. 



Teeth 10.0 Bile 88.0 



Bones 13.0 Milk 88.7 



Cartilage 55.0 Pancreatic juice. ... 90.0 



Muscles 75-o Urine 93 . 6 



Ligament 76.8 Lymph 96.0 



Brain 78.9 Gastric juice 97.5 



Blood 79-5 Perspiration 98 . 6 



Synovia 80 . 5 Saliva 99-5 



In all the fluids and tissues of the body blood, lymph, muscle, gland, 

 etc. water acts the part of a general solvent, and by its means alone circula- 

 tion of nutrient matter is possible. It is the medium also in which all fluid 

 and solid aliments are dissolved before absorption, as well as the means by 

 which all, except gaseous, excretory products are removed. All the various 

 processes of secretion, transudation, and nutrition depend of necessity on 

 its presence for their performance. 



The greater part, by far, of the water present in the body is taken into 

 it as such from without, in the food and drink. A small amount, however, 

 is the result of the chemical union of hydrogen with oxygen in the oxidations 

 of the body. 



The loss of water from the body is intimately connected with excretion 



