INVARIABLE QUANTITY OF ALKALINE BASES. 6* 



Of course, this argument refers only to those alkaline bases 

 which in the form of organic salts form constituents of the plants. 

 Now, these salts are preserved in the ashes of plants as carbon- 

 ates, the quantity of which can be easily ascertained. The 

 bases contained in the bark do not any longer belong to the vital 

 organism of the plant. 



It has been distinctly shown, by the analyses of De Saussure 

 and Berthicr, that the nature of a soil exercises a decided influ- 

 ence on the quantity of the different metallic oxides contained in 

 the plants which grow on it ; that magnesia, for example, was 

 contained in the ashes of a pine-tree grown at Mont Breven, 



particular acid 51'6 parts of magnesia have been used, we may be perfectly 

 certain that tbe same quantity of this acid will be exactly neutralized by 

 78 parts of soda. 



We have now to state the causes which occasion this unequal power of 

 these metallic oxides to neutralize acids We have also to explain why, to 

 produce the same effect, it is necessary to employ a smaller quantity of soda, 

 and only one half the quantity of magnesia that we would use of potash, 

 and still that the relative quantities are constant with all acids. 



A knowledge of the composition of the bases has afforded us a very sim 

 pie explanation of these causes. All the bases now mentioned contain 

 oxygen combined with a metal ; and their capacity of saturation depends 

 upon the quantity of oxygen contained within them. 



Although the absolute quantities of the above bases are so very different, 

 they all contain the same quantities of oxygen. 



Oxvgen contained. 

 100 Sulphuric Acid neutralize 118 Potash = 20 

 100 " " " 78 Soda = 20 



100 " " " 71"2 Lime = 20 



100 " " " 51-6 Magnesia = 20 



Now, if we neutralize 100 parts of sulphuric acid with potash and soda, 

 or with potash, soda, and lime, or with potash, soda, lime, and magnesia, 

 the sulphuric acid unites with quantities of two, three, or four bases exactly 

 corresponding to their united quantity of oxygen. This may be represent- 

 ed in the following table : — 



100 parts sulphuric acid neutralize < Sodium* \ ^ P ar * s oxygen. 



C Potassium } 



100 " " " " < Sodium V 20 " oxygen. 



f Calcium ) 



(Potassium ^ 

 CakX 2 ° " °™« n - 



[ Magnesium 



