CHEMICAL COMPOSITION OF THE BODY 



27 



Water, for example, as it leaves the body as perspiration, 

 is made of hydrogen and oxygen, the same as water from a 

 faucet. The juices formed in the stomach are partly made 

 of hydrochloric acid, the same as that used in various manu- 

 facturing processes. Much of the material in bones is lime; 

 some of the material in blood is iron, and it becomes red when 

 mixed with oxygen, the same as iron does when it rusts. 

 Salt is easily noticed in perspiration and tears, and has the 

 same composition as table salt. 



Living matter contains but a small number of the seventy- 

 seven elements referred to above; those commonest in the 

 body are carbon, hydrogen, oxygen, nitrogen, calcium, phos- 

 phorus, sulfur, sodium, chlorine, fluorine, potassium and 

 iron. The following table shows approximately the per- 

 centage in which each occurs: 



CHEMICAL COMPOSITION OF THE BODY 



These are the same chemical elements which we should 

 find if we analyzed materials all around us in nature; e.g. 

 air, water, soil or rocks. The living body is thus constructed 

 of the same materials as are found in non-living, inanimate 

 bodies. But there must be some difference. What is it? 



