38 THE FEEDING OF ANIMALS 



ASH 



The ash or mineral part of plants and animals has 

 occupied a minor place in the discussions which pertain 

 to the principles and problems of animal nutrition. In the 

 past chief attention has been given to the carbon com- 

 pounds of living organisms, while the compounds of the 

 mineral world, in their relation to foods and to nutritive 

 processes, have generally been passed by with too brief 

 discussion. It is desirable to gain a clear understanding 

 of the combinations, distribution, and functions of the 

 constituents of the ash, for their importance in animal 

 nutrition is no less than pertains to the carbon compounds. 



48. Mineral compounds in the ash of plants and 

 animals. As previously stated, the mineral portion of a 

 plant or animal is measured by the ash or residue after 

 combustion, the principal ingredients of which are the 

 following: 



TABLE X 

 Adds Bases 



Hydrochloric acid . . . HC1. Potash K 2 O 



Sulfuric acid H 2 SO 4 Soda Na^O 



Phosphoric acid . . . H6P 2 C>8 Lime CaO 



Silicic acid SiO 2 Magnesia MgO 



Carbonic acid .... CO 2 Iron oxid Fe 2 O 3 



Other mineral compounds are found in the various 

 forms of vegetable life, but those mentioned are all that 

 we need to discuss at length. 



The acids and bases do not exist in the ash as shown, 

 but they are united to form salts, and so we have the 

 chlorides, sulfates, phosphates, and carbonates of potas- 

 sium, sodium, calcium, magnesium, and iron. These 

 are nearly all familiar objects in common life, as, for 

 instance, sodium chloride (common salt), potassium 



