CHAPTER IX 



STATICS 



Oxidation. In the preceding chapter, the question of nutri- 

 tion was considered from a purely qualitative point of view. 

 In order to understand the quantitative relationships it is 

 necessary to consider the potential energy of the food as a 

 whole and of the several constituents. 



By potential energy of the food is meant the energy which 

 is liberated, i.e. converted into the kinetic form, when the food 

 is oxidised. The amount of potential energy of any food must 

 therefore bear some relation to the amount of oxidation of 

 which the food is capable. All the constituents protein, fat, 

 and carbohydrates of the food are already partially oxidised, 

 i.e. they contain some oxygen, but in very different degree, 

 and require different amounts of oxygen to complete the 

 change. This may be seen, perhaps most clearly, from the 

 percentage composition of the compounds. 



There is but little difference in the percentage composition 

 of the several kinds of fat and of the several kinds of carbo- 

 hydrate ; but the percentage composition of the former is very 



"5 



