PREFACE. xxi 



aim to reach both the students in his own classes and in the 

 agricultural colleges generally, as well as the fast increasing 

 class of farmers of both regions who are willing and even 

 anxious to avail themselves of the results and principles of 

 scientific investigation, without " shying off ' from the new 

 or unfamiliar words necessary to embody new ideas. It 

 would seem to be time that the latter class, and more especially 

 those constituting farmers' clubs, should learn to understand 

 and appreciate both the terms and methods of scientific reason- 

 ing, which are likely to form, increasingly, the subjects of in- 

 struction in the public schools. But in order to segregate to 

 some extent the generally intelligible matter from that which 

 requires more scientific preparation than can now be generally 

 expected, it has been thought best to use in the text two kinds 

 of type ; the larger one embodying the matter presumed to be 

 interesting and intelligible to the general reader, while the 

 smaller type carries the illustrative detail and discussion which 

 will be sought chiefly by the student. 



As regards the chemical nomenclature used in this volume, 

 the writer has not thought it advisable to follow the example 

 set by some late authors in substituting for the well-known 

 names of the bases and acids, those of the elements, and still 

 less, those of the intangible ions. Any one who has taught 

 classes in agricultural chemistry will have experienced the 

 difficulty and loss of time unnecessarily incurred in the inces- 

 santly recurring transposition of terms, and complication of 

 formulae, serving no useful purpose save that of academic con- 

 sistency. It is of at least doubtful utility to present to the 

 farmer, e. g., the inflammable and dangerous elements phos- 

 phorus and potassium as prime factors in the success of his 

 crops, and of healthy nutrition. 



Inasmuch as all the elements are presented to and con- 

 tained in the plant in compounds only, and these compounds are 

 themselves, in the dilute solutions used by plants, known to be 

 largely dissociated into their basic and acid groups, it seems to 

 be most natural to present them under the corresponding, even 

 if not absolutely theoretically correct names of acids and bases, 

 to which the farmer and the trade have been accustomed for 

 half a century. Upon these considerations the long-used 

 designations of potash, soda, lime, phosphoric, sulfuric, nitric 



