14 THE HUMAN BODY, 



important is carbonic dioxide (CO*), which is the form in 

 which by far the greater part of the carbon taken into the 

 Body ultimately leaves it. United with calcium it is found 

 in the bones and teeth in large proportion. 



Formic. Acetic, and Butyric acids also are found in the 

 Body; stearic, palmitic, and oleic have been above men- 

 tioned as obtainable from fats. Lactic acid is found in the 

 stomach and develops in milk when it turns sour. A body 

 of the same percentage composition, CsHeOs (sarcolac- 

 tic acid), is formed in muscles when they work or die. 



Glycero-phosphoric acid (C 3 H 9 P0 6 ) is obtained on the 

 decomposition of lecithin, a complex nitrogenous fat found 

 in nervous tissue. 



Inorganic Constituents. Of the simpler substances en- 

 tering into the structure of the body the following are the 

 most important: 



Water; in all the tissues in greater or less proportion 

 and forming about two thirds of the weight of the whole 

 Body. A man weighing 75 kilos (165 Ibs.), if completely 

 dried would therefore lose about 50 kilos (110 Ibs.) from the 

 evaporation of water. Of the constituents of the Body the 

 enamel of the teeth contains least water (about two per 

 cent) and the saliva most (about 99.5 percent); between 

 these extremes are all intermediate steps bones containing 

 about 22 per cent, muscles 75, blood 79. 



Common salt Sodium chloride (NaCl) ; found in all 

 the tissues and liquids, and in many cases playing an 

 important part in keeping other substances in solution in 

 water. 



Potassium chloride (KC1); in the blood, muscles, nerves, 

 and most liquids. 



Calcium phosphate (Ca 3 2P0 4 ); in the bones and teeth in 

 large quantity. In less proportion in all the other tissues. 



Besides the above, ammonium chloride, sodium and 

 potassium phosphates, magnesium phosphate, sodium sul- 

 phate, potassium sulphate and calcium fluoride have been 

 obtained from the body. 



Uncombined Hydrochloric acid (HC1) is found in the 

 stomach. 



