898 LIEBIG DEMONSTRATES THAT ANIMAL HEAT 



contained in the daily food of a German soldier 

 would, on uniting with atmospheric oxygen, afford 

 heat enough by respiration to raise 1 oz. of water 

 197,477, and 370 Ibs. of water from 32 to 98-3 : 

 that if the quantity of heat carried off with 

 3 Ibs. of water in the form of vapour, from the 

 lungs and skin, be 51,1097, there will remain 

 146,380 for maintaining the temperature of the 

 body, independent of what is obtained from the 

 combustion of hydrogen. He therefore concludes 

 that animal heat is derived wholly from the action 

 of oxygen on the combustible elements of food, or 

 of the structures formed from it, as was long ago 

 maintained by Black, Crawford, Lavoisier, Dai- 

 ton, and many other distinguished chemists: 

 that it is not generated by nervous influence, 

 motion of the blood, secretion, nutrition, muscu- 

 lar motion, galvanic action, &c.* 



But although Liebig has more clearly ex- 



* In reply to the doctrine of Dulong and Despretz, that 10 per 

 cent, more heat is given off by animals than corresponded to the 

 amount of oxygen consumed, Liebig observes very justly, that 

 while surrounded by water at 47 '5, as in the experiments of 

 Despretz, the temperature of the water was raised at the expense 

 of the animals, which were proportionally cooled ; and that if 

 the wind-pipe had been tied, there would have been a rise of 

 temperature in the water without any consumption of oxygen. 

 Dumas also maintains that it is the cooling of the animal not 

 taken into the account by Dulong and Despretz, which expresses 

 the excess of heat that has been attributed by them and other 

 physiologists to a peculiar power in the system, independent of 

 respiration. 



