INVARIABLE QUANTITY OF ALKALINE BASES. 69 



cent of soluble salts. A greater difference in the proportion of 

 the alkaline bases could scarcely exist between two totally dif- 

 ferent plants, and yet even here the quantity of oxygen in the 

 bases of both was the same. 



100 parts of the ashes of firwood from Allevard contained, 

 according to Berthier (Ann. de Chim. et de Phys., t. xxxii., 

 P. 248), 



Potash and Soda 16*8 in which 3*57 parts must be oxygen 

 Lime . . 29'6 " 8*36 " " 



Magnesia . 33 " 126 " «« 



49-7 13-19 



Only part of the potash and soda in these ashes was in com- 

 bination with organic acids ; the remainder was in the form of 

 sulphates, phosphates, and chlorides. One hundred parts of 

 the ashes contain 0*797 sulphuric acid, 3-12 phosphoric acid, 

 and 0*077 hydrochloric acid, which together neutralize a quan- 

 tity of base containing 0*53 oxygen. This number, therefore, 

 must be subtracted from 13*19. The remainder, 12*66, indi- 

 cates the quantity of oxygen in the alkaline bases, combined 

 with organic acids in the firwood of Allevard. 



The firwood of Norway contained in 100 parts, — 



52-75 13*21 



And if we subtract from 13*21 the quantity of oxygen of the 

 bases in combination with sulphuric and phosphoric acid, viz., 

 0*79, 12*42 parts remain as the amount of oxygen contained in 

 the bases which were in combination with organic acids. 



These remarkable approximations cannot be accidental ; and 

 if future investigations confirm them in other kinds of plants, no 

 other explanation than that already given can be adopted. 



It is not known in what form manganese, and oxide of iron, 

 are contained in plants ; but we are certain that potash, soda, 



