UNIVERSITY 



OF 



AGRICULTURAL CHEMISTRY. 



CHAPTEE I. 

 INTRODUCTION. 



CHEMISTRY has an intimate connection with all the operations 

 of life, both animal and vegetable. The processes involved in 

 vital phenomena are attended by chemical changes so complex 

 in character that they are often difficult to unravel. Conse- 

 quently it is found that while the chemical reactions occurring 

 in most industries are thoroughly understood and can be satis- 

 factorily explained, those attending the growth of animals and 

 plants are, to a great extent, unknown, indeed in many cases 

 appear to be contrary to the ordinary laws of chemistry. Thus 

 an elementary knowledge of the science suffices in the case of 

 many industrial operations to give a rough, superficial explana- 

 tion of the chemical changes involved, whereas in studying the 

 phenomena of life instances soon present themselves, in which 

 reactions, of a kind altogether unexpected from an ordinary 

 laboratory student's point of view, occur. So too in the re- 

 actions taking place in a soil it is often found that the time 

 required is so long and the dilution of the solution so great 

 that the direction of the change is to be attributed to mass 

 action or other somewhat complex cause rather than to the 

 ordinary influences governing a chemical reaction. Agricul- 

 tural chemistry therefore, since it deals mainly with the changes 

 occurring in the soil, the growth and life of plants, the feeding 

 of animals and the preparation of food products, is frequently 

 called upon to explain changes of the character described; a 

 task which is often difficult and requires a knowledge of 

 physical chemistry. 



