. HAP. ii OXIDATION LIFE 



p.i>t a^c. (icnerally speaking, when elements or simple com- 

 pounds are united into complex compounds, energy is stored 

 up, and when oxidation takes place and these compounds are 

 broken down into simpler compounds again, such, for instance, 

 a-, carbonic acid and water, the energy is again set free. 



The dead body of an animal also consists of substances 

 formed by the union of carbon and hydrogen and other elements 

 into very complex compounds. If the dead body be burnt, 

 oxygen unites with these elements, oxidation takes place, 

 carbonic acid and water are formed, and only a small amount 

 of incombustible material remains, just as in the case of coal the 

 a-lies remain. The heat given out when the body is burnt is the 

 energy set free by the oxidation of the complex chemical sub- 

 stances. The dead body and the piece of coal give out no 

 energy or heat till oxidation takes place, and till then they are 

 as cold as other things around them. 



The living body of an animal consists of the same complex 

 substances as a dead body, but it differs from the dead body 

 , in being warm, and usually warmer than the lifeless things 

 around it. It is warm because it is constantly giving out 

 energy as heat. The complex substances of the living body 

 are constantly breaking down, and their oxidation is constantly 

 taking place, forming in the same way carbonic acid and water. 

 The breaking down of the complex substances and the oxida- 

 tion in the living lx>dy are, however, taking place gradually, 

 so that the energy is set free little by little, and therefore the 

 amount of heat given off at any one time is small. Thus the 

 temperature produced is only a little above that of surrounding 

 objects, while the oxidation which takes place when the dead 

 body is burnt is sudden and intense, and so a high tempcra- 

 V' Hire is produced. A high temperature is produced when a 

 dead body is burnt because all the energy stored up is given 

 out in a very short time. When the dead body of an animal 

 decays, an extremely slow oxidation of the substances com- 

 posing the body goes on ; carbonic acid, water, and ammonia 

 arc formed, and mostly pass away, until almost the same 

 remnant is left the ashes, just as if it had been burnt. The 

 energy it gives off during the slow process in the one case is 

 much the same in total amount as that given off all at once lo 

 form the white heat of the flame in the other case. 



