PEEFAOE. 



IN the sixteen years which have intervened between this 

 work and the sixth edition of my ' Chemistry applied 

 to Agriculture and Physiology,' I have had sufficient op- 

 portunity to become acquainted with all the obstacles 

 which are opposed to the introduction of scientific teach- 

 ing into the domain of practical agriculture. Among 

 the chief of these may be reckoned the complete sep- 

 aration which has always existed between science and 

 practice. 



There has generally prevailed an idea that a smaller 

 amount of information and intelligence is required for agri- 

 cultural pursuits than for any other occupation ; nay, that the 

 practical skill of the farmer is only likely to be injured 

 when he has recourse to science. * Whatever requires 

 thought and reflection is regarded as theory, which being 

 the opposite of practice, must, of course, be of little value. 

 The natural result of such opinions is, that when the prac- 

 tical man does attempt to apply scientific teaching, he is 

 almost invariably a sufferer. He seems altogether to for- 

 get that man does not become intuitively acquainted with 

 scientific teaching, which, like the skilful use of any com- 

 plex instrument, must be learned. 



The truth or error of the notions which guide our prac- 

 l* 



