NEW YOl 



BOTANIC. 

 GARDE* 



PREFACE 



Iii this publication are presented the results of an investigation 

 which was proposed by Mr. Crawley, Director of this Station, and the 

 writer wishes to express his thanks to him for many valuable sugges- 

 tions made during the progress of the work. 



As probably some of the readers for whom this bulletin is prim- 

 arily i nl ended may not be familiar with chemistry, the author has en- 

 deavored to use chemical terms as little as possible. But the very 

 nature of the subject is such that they cannot be entirely avoided; and 

 for the benefit of those who have only a slight knowledge of such terms, 

 a few explanations may not be out of place. Most agricultural workers 

 nowadays know what is meant by those terms which designate the dif- 

 ferenl chemical substances that form the important parts of soils, such 

 as lime, nitrogen, phosphoric acid and potash. But they may not be 

 so well acquainted with some words from the 7 chemical vocabulary which 

 the writer has had to make use of in this publication. It would ob- 

 viously be out of place here to attempt giving a detailed account of all 

 these terms, and strict scientific accuracy will have to be sacrificed to 

 brevity and conciseness. 



By the term "salt" which is so much used in this bulletin, the 

 chemist designates a substance which may be considered as consisting 

 of two components in a very firm combination. One of these compo- 

 nents is usually some metal, as for instance sodium, potassium, calcium, 

 magnesium, iron, aluminium, etc., and the other component is either a 

 non-metalic element, as for instance chlorine, or a combination of such 

 p non-metalic element with the element oxygen. The metals which are 

 the elements characteristic of basic substances, like caustic soda or quick 

 lime, are in this bulletin termed "basic radicles", and the other radicles 

 which are characteristic of acids like carbonic, sulfuric, hydrochloric, 

 etc.. are called "acid radicles". The combinations of basic and acid 

 radicles are called salts, like sodium sulfate, calcium chloride, etc. One 

 acid and one base may forjn several salts by combining in different well 

 defined proportions. Thus sodium bicarbonate contains only one car- 

 bonic acid radicle for one of sodium, whereas sodium carbonate has one 

 for two of sodium. In chemical analysis it is necessary to 

 "determine the acid radicles by themselves and the basic radicles 

 by themselves, and their sum total gives the total quantity 

 of salts present, which may exist there in a number of 



