APPLICATION OF CHEMISTRY TO AGRICULTURE. 417 



stance necessary for the existence of most plants ; indeed, it has 

 been already shown that the potash may be replaced, in many 

 cases, by soda, magnesia, or lime.&quot;* 



LXXIV. APPLICATION OF CHEMISTRY TO AGRI 

 CULTURE. 



It must not be inferred, from any remark which has fallen from 

 me, that I overlook the value of chemical science and inquiry in 

 respect to agriculture. An inference of that nature would do me 

 a great injustice. Our obligations in this matter are already very 

 great, and more and wider triumphs are to be looked for. But two 

 or three things, in this case, appear to me deserving of considera 

 tion, and likely to moderate an excessive confidence. The first 

 is, that vegetation, and consequently cultivation, in the most scien 

 tific sense of the term, is not so simple a matter as some persons 

 would have us imagine. How, for example, particular plants from 

 the same soil are capable of extracting entirely different sub 

 stances, according to their own peculiar and individual charac 

 ters, each one preserving its own identity in form, taste, odor, 

 color, fruit, and use, is not yet explained. The explanation is not 

 even approached. In the second place, it seems assuming quite 

 too much to suppose that all the processes of vegetation are to be 

 resolved into mere chemical processes understanding by chem 

 ical processes those laws or operations of which chemistry has 

 attained a knowledge. The remarks which I have just made 

 seem to demonstrate this. In the next place, the knowledge 

 which chemistry has already furnished, either of the nature of 

 soils or manures, or of the phenomena of vegetation, has not as 

 yet been of so practical a character as is to be hoped for ; and it 

 would seem extremely difficult, not to say impossible, to meet on 

 any extended scale the diversities of soil which it has illustrated.. 

 The newly-invented manure, to which I have above referred, 

 should it be found to equal what it seems to promise, may 

 fully meet this objection, and thus effect an important stride 

 in agricultural improvement. 



* Liebig. 



