58 PHILOSOPHY OF ZOOLOGY. 



abundant in animal fluids. It is much more common in 

 the vegetable kingdom, especially in land plants. 



11. Soda. This alkali is present in all the fluids in va- 

 rious states of combination, and is more abundant than the 

 preceding. It gives to many of the secretions the alkaline 

 property of changing vegetable blues into green. It is 

 found in union with the carbonic, phosphoric, sulphuric, 

 and muriatic acids. 



12. Ammonia. As the elements of this alkali exist in all 

 the fluids, and many of the solids of animals, it is frequently 

 produced during putrefaction, and the decompositions of 

 analysis. These elements are likewise found united in the 

 system, and the alkali then appears in union with the va- 

 rious acids, as the phosphoric, muriatic, and lactic. 



13. Lime. This earth, of which the hard parts of ani- 

 mals, such as bones and shells, are chiefly composed, is of 

 universal occurrence. It is always in a state of combina- 

 tion, and chiefly with the carbonic or phosphoric acids. 



14. Magnesia. In the animal system, this earth occurs 

 sparingly. It has been detected in the bones, blood, and 

 some other substances, but always in small quantity, and 

 chiefly in union with phosphoric acid. 



15. Silica. This earth occurs still more sparingly than 

 the preceding. It is found in the hair, urine, and urinary 

 calculi. 



16. Iron. The existence of iron has hitherto only been 

 detected in the colouring matter of the blood, in bile, and 

 in milk. Its peculiar state of combination in the blood, has 

 given rise to various conjectures ; but a satisfactory solution 

 of the question has not as yet been obtained. In milk, it 

 appears to be in the state of phosphate. 



17. Manganese. The oxide of this metal has been ob- 

 served, along with iron, in the ashes of hair, by VAUCUJE- 

 LIN. 



