INORGANIC CONSTITUENTS. 



373 



General View of the Chemical Constituents of 

 the Organism. 



247. (A) INORGANIC CONSTITUENTS. I. Water forms 58 '5 per cent, of the whole 

 body, but it occurs in different quantity in the different tissues. The kidneys contain the 

 most water, 827 per cent. ; bones, 22 per cent. ; teeth, 10 per cent. ; while enamel contains 

 the least, 0*2 per cent. ( 229). According to some observers, peroxide of hydrogen (H 2 2 ) is 

 also present in the body. 



[Approximately, water forms about two-thirds of the weight of the body, so that a body 

 weighing 75 kilos. (165 lbs.) contains 50 kilos. (110 lbs.) of water. The following table, 

 modified from Beaunis, shows the percentage of water in several tissues and organs : 



Tissue or Organ. 



Enamel, 



Dentine, 



Bone, 



Fat, 



Elastic tissue, 



Cartilage, 



Liver, . 



Water. 

 2 

 lO'O 

 48-6 

 29-9 

 49-6 

 55-0 

 69-3 



Blood, . .79-1 

 Bile, . .86-4 

 Milk, . .89-1 

 Liquor sanguinis, 90 "1 

 Chyle, . .92-8 



Solids. 

 99-8 

 90-0 

 51-4 

 70-1 

 50-4 

 45-0 

 307 



20-9 

 13-6 

 10-9 



Tissue or Organ. 

 Spinal cord, . 

 White matter 

 of brain, . 

 Skin, . 

 Brain, . 

 Muscles, 

 Spleen, 



Solids. 



Water. 

 697 

 70-0 



72-0 

 75-0 



757 

 75-8 



Liquids. 



7'2 



Lymph, 

 Serum, . 

 Gastric juice, . 

 Intestinal juice, 

 Tears, . 



95-8 

 95-9 

 97-3 

 97-5 



98-2 



Solids. 

 30-3 



30-0 



28-0 

 25-0 

 24-3 

 24-2 



4-2 

 4-1 

 2-7 

 2-5 

 1-8 



II. Gases. O, -ozone ( 37) - H. - N - C0 2 ( 38). Marsh gas CH 4 ( 124), NH 3 ( 30, 

 124, 184), H 2 S ( 184). 



III. Salts. Sodium chloride [is one of the most important inorganic substances present in 

 the body. It occurs in all the tissues and fluids of the body, and plays a most prominent part 

 in connection with the diffusion of fluids through membranes, and its presence is necessary for 

 the solution of the globulins (p. 376). Sometimes it exists in a state of combination with 

 proteid bodies, as in the blood-plasma. Common salt is absolutely necessary for one's existence ; 

 if it be withdrawn entirely, life soon comes to an end. About 15 grammes are given off in 

 twenty-four hours, chiefly by the urine. Boussingault showed that the addition of common 

 salt to the food of cattle greatly improved their condition]. 



[Calcium phosphate (Ca 3 P 2 8 ) is the most abundant salt in the body, as it forms more than 

 one-half of our bones, but it also occurs in dentine, enamel, and to a much less extent in the 

 other solids and fluids of the body. Amongst secretions, milk contains relatively the largest 

 amount (272 per cent.). In milk it is necessary for forming the calcareous matter of the bones 

 of the infant. It gives bones their hardness and rigidity. It is chiefly derived from the, 

 food, and, as only a small quantity is given off in the excretions, it seems not to undergo rapid 

 removal from the body.] 



[Sodium phosphate (PNa 3 4 ), acid sodium phos2)hate (PNa 2 H0 4 ), acid potassium phosphate 

 (PK 2 H0 4 ). The sodium phosphate and the corresponding potash salt give most of the fluids 

 of the body their alkaline reaction. The alkaline reaction of the blood-plasma is partly due to 

 alkaline phosphates, which are chiefly derived from the food. The acid sodium phosphate is the 

 chief cause of the acid reaction of the urine. A small quantity of phosphoric acid is formed in 

 the body owing to the oxidation of lecithin, which contains phosphorus.] 



[Sodium carbonate (Na 2 C0 3 ) and sodium bicarbonate (NaHC0 3 ) exist in small quantities in 

 the food, and are formed in the body from the decomposition of the salts of the vegetable acids. 

 They occur in the blood-plasma, where they play an important part in carrying the C0 2 from 

 the tissues to the lungs.] 



[Sodium and potassium sulphates (Na 2 S0 4 and K 2 S0 4 ) exist in very small quantity in the 

 body, and are introduced with the food, but part is formed in the body from the oxidation of 

 organic bodies containing sulphur.] 



[Potassium chloride (KC1) is pretty widely distributed, and occurs specially in muscle, 

 coloured blood-corpuscles, and milk. Calcium fluoride (CaFl 2 ) occurs in small quantity in 



