riii PREFACE. 



were carried on in the Laboratory of this place, with the sole 

 object of giving a firmer basis to my exposition of the causes of 

 the advantageous results attending the practice of rotation of 

 crops, and also of effectually banishing all doubts concerning 

 their accuracy. 



In my "Chemistry in its applications to Physiology and 

 Pathology," I have subjected the process of nutrition of the 

 animal organism to a stricter investigation ; and I am now, for 

 the first time since the completion of these labors, in a situation 

 to give a simple and determinate expression to my view of the 

 origin of animal excrements, and of the cause of their beneficial 

 effects on the growth of all vegetables. 



Now that the conditions which render the soil productive and 

 capable of affording support to plants, are ascertained, it cannot 

 well be denied that from Chemistry alone further progress in 

 Agriculture is to be expected. 



Every unprejudiced person will, I trust, be finally convinced 

 by this third edition, that I have earnestly endeavored to perfect 

 my views, and have striven, with the best intentions, to ascertain 

 truth and obviate error. 



JUSTUS LIEBIG. 



GlKSSKN, 



A Mfust, 1843. 



