42 The Feeding of Animals 



shown, but they are united to form salts, and so we 

 have the chlorides, sulfates, phosphates, and carbon- 

 ates of potassium, sodium, calcium and magnesium. 

 These are nearly all familiar objects in common life, 

 as, for instance, sodium chloride (common salt), potas- 

 sium chloride (the muriate of potash of the market), 

 potassium sulfate (the sulfate of potash of the market), 

 calcium sulfate (of which gypsum or land plaster is 

 composed), calcium phosphate (burned bone is chiefly 

 this compound), potassium phosphate (a compound of 

 phosphoric acid and potash found chiefly at the drug- 

 gist's) and calcium carbonate (limestone). It should be 

 remembered that the compounds in the ash are not 

 necessarily those of the plant or animal. During the 

 process of ignition of plant or animal substance, or- 

 ganic compounds are broken up, certain acid and basic 

 elements of which enter into combination in the salts 

 of the ash. Much of the lime in the ash is in union 

 with carbonic acid, which in the plant may have been 

 associated with vegetable acids, such as oxalic and 

 tartaric, and at least part of the sulfur and phos- 

 phorus of the ash comes from the nitrogen com- 

 pounds. 



The salts of the ash differ greatly in their properties. 

 Some are soluble in water, others are not. To the 

 former class belong all the chlorides, and the potas- 

 sium and sodium sulfates and phosphates. The normal 

 phosphates of calcium and magnesium are insoluble 

 in water, but soluble in various acids. These facts are 

 important in showing what salts may be found in the 

 plant and animal juices, and what effect leaching with 



