FIRST BOOK. 

 CHEMISTRY OF PLANTS. 



CHAPTER I. 



THE INORGANIC ELEMENTS. 



5. THE elementary bodies found in plants are the following : 

 1. Carbon (C) ; 2. Hydrogen (H); 3. Oxygen (O); 4. Nitro- 

 gen (N); 5. Chlorine (Cl) ; 6. Iodine (I) ; 7. Bromine (Br) ; 8. 

 Sulphur (S); 9. Phosphorus (P) ; 10. Silicium (Si) ; 11. Potas- 

 sium (K); 12. Sodium (Na); 13. Calcium (Ca); 14. Magnesium 

 (Mg) ; 15. Aluminium (Al); 16. Iron (Fe) ; 17. Manganese (Ma) ; 

 18. Copper (Cu). 



These substances occur in very varying proportions in plants. Car- 

 bon is of all the most important and the most abundant. It forms the 

 skeleton, the solid basis, of all plants. By careful charring, the minutest 

 parts of the texture of plants may be preserved, and almost everything 

 is consumed or driven off except the Carbon. In the spontaneous de- 

 composition of plants, it also remains longest unchanged ; and the entire 

 structure of the plant is often retained in peat and coal, so that the 

 families and genera of the plants can be recognised. Carbon is never 

 found pure in plants. 



Hydrogen and Oxygen form, with Carbon, most of the proximate 

 principles of plants, and in the more important substances they occur 

 in the proportion in which they form water. Oxygen is found free 

 in plants dissolved in their juices. Hydrogen is also found free in the 

 Fungi. 



Nitrogen in combination with the foregoing elements form some of 

 the most important secretions of plants. Whether it is found free in the 

 Fungi, is not yet well made out. 



Chlorine, Iodine, and Bromine, are found in the form of salts. The 

 first in plants of the sea-shore ; the two last in those growing in the sea. 



Sulphur and Phosphorus are found in most plants as sulphuric and 

 phosphoric acids (the last is especially abundant in the membranes of the 

 seed in grasses). They both enter into combination with protein to form 

 albumen, casein, &c. 



Silicium is present in all plants as silica ; often in very large quan- 

 tities, as is shown by the following analysis of the ashes of several 

 plants : 



B 2 



