«6 OF THE INORGANIC CONSTITUENTS OF PLANTS. 



Now, as we know the capacity of saturation of organic acids 

 to be unchanging, it follows that the cuantity of the bases united 

 with them cannot vary ; and for this reason the latter substances 

 ought to be considered with the strictest attention, both by the 

 agriculturist and physiologist. 



We have no reason to believe that a plant in a condition of 

 free and unimpeded growth produces more of its peculiar acids 

 than it requires for its own existence ; hence, a plant, on what- 

 ever soil it grows, must contain an invariable quantity of alkaline 

 bases. Culture alone will be able to cause a deviation. 



In order to understand this subject clearly, it will be necessary 

 to bear in mind that any one of many of the alkaline bases may 

 be substituted for another, the action of all being the same. Our 

 conclusion is, therefore, by no means endangered by the exist- 

 ence in one plant of a particular alkali which may be absent in 

 others of the same species. If this inference be correct, the 

 absent alkali or earth must be supplied by one similar in its mode 

 of action, or in other words, by an equivalent of another base. 

 The number of equivalents of these various bases which may be 

 combined with the acid in a given plant must consequently be a 

 constant quantity, and therefore the amount of oxygen contained 

 in them must remain unchanged under all circumstances and on 

 whatever soil they grow.* 



* When sulphuric acid is placed in contact with potash, soda, lime, or 

 magnesia, the properties both of the acid and of the alkali disappear, and 

 if the proportions have been just, the compound thus produced is a neutral 

 sulphate of these bases. 



100 parts of sulphuric acid require for neutralization very different quanti- 

 ties of the above bases; thus, to effect this purpose, it is necessary to em- 

 ploy 118 parts of potash, 7S parts of soda, 71 "2 parts of lime, and 51 '6 parts 

 of magnesia. 



In order to produce a neutral nitrate with 118 parts of potash (the quan- 

 tity necessary to saturate 100 parts of sulphuric acid), we must employ 135 

 parts of nitric acid. Now, when we examine how much soda, lime, or 

 magnesia is required to saturate the same quantity of nitric acid (135 parts) 

 it is found that complete saturation is effected by 7S of soda, 71*2 of lime, 

 51*6 of magnesia, or exactly the same quantities as in the case of sulphuric 

 acid. It is quite indifferent what acids we use to neutralize their bases, or 

 how much the numbers obtained may differ from those now stated ; still 

 the relative proportion remains invariable. If for the saturation of any 



