152 CHEMISTRY. 



this heat the same chemical unions take place as in the burn- 

 ing of a common candle. We have told you something al- 

 ready about the introduction of oxygen into the body in 

 breathing. It enters the blood in the lungs, and courses 

 about in search of carbon and hydrogen. It finds these 

 every where, and unites with them, forming with the car- 

 bon carbonic anhydride, and with the hydrogen water, as 

 in the case of the candle. In effecting this union heat is 

 produced, and thus the body is kept warm. 



198. The Lungs not the Body's Furnace. It was for a 

 long time supposed that the chemical combinations produc- 

 ing the heat occurred in the lungs, and that the heat gener- 

 ated there was carried with the blood all over the body. 

 But there were some facts observed that were inconsistent 

 with this doctrine. If it were the true doctrine, the lungs 

 should be hotter than any other organ in the body, just as 

 a furnace is always hotter than the apartments to which the 

 heat from it is carried. But it was found that the lungs 

 were no warmer than other organs, and that therefore they 

 were not the furnace of the body. Then, again, it was ob- 

 served that the heat of different parts of the body is often 

 temporarily increased. Thus when an inflammation occurs 

 there is more heat than usual. So, also, blushing will make 

 the face to burn. In such cases the increased heat is of 

 course produced where it manifests itself, and not in the 

 lungs. It was therefore found, on further investigation, that 

 the animal heat is produced in all parts of the body, every 

 little vessel being a chemical laboratory for this as well as 

 other purposes. 



199. Temperature of the Body. The heat of the body is 

 maintained quite uniformly at 98.* You observe that this 



* The temperatures named in this section are given in Fahrenheit de- 

 grees. See Appendix. 



