CONTENTS. 



CHAPTER I. 



Gkologt of Soil Page 17 



Objects of agricultural chemistry ; objects and nature of agricultural geology ; 

 definition of the terms, primary and secondary ; rocks have one common origin ; 

 the terms primary and secondary soil are useless ; rocks and soil are to be classed 

 by their origin and distribution ; in their origin all rocks are igneous or by fire ; 

 chemical constitution of all rocks similar ; there is one rock and one soil ; chem- 

 ical constitution of rocks does not affect the vegetation over them ; geographical 

 distribution of plants ; the laws which govern it ; rocks do not form the soil 

 which covers them ; general uniformity of chemical composition of foil ; proofs 

 of general uniformity of composition ; from Massachusetts soil, 146 specimens, 

 and from various parts of the world, 267 specimens ; remarks on soil analyses, 

 all are imperfrct approximations only to truth ; the largest portion of soil, least 

 liable to be affected by different modes of analysis ; by any mode, soil divides 

 itself into two portions — soluble and insoluble ; several elements in soil often 

 educed by analysis, which should be included in the insoluble portion of soil ; 

 carbonate of lime, too often a product, not an educt of analysis ; potash and 

 soda of soil to be considered generally as combined with the organic matter ; 

 clay, iron, magnesia to be included in the insoluble ingredients ; plaster, phos- 

 phate of lime, or bone-dust in the soluble ingredients of soil ; division of ele- 

 ments of soil into soluble, insoluble, and salts of lime ; table of analyses of 413 

 soils from all parts of the world ; principles deduced from this table and its re- 

 sults ; rule for calculating the amount per acre from results per l(tO parts of 

 soil ; analyses of vine grown on soils formed from different geological districts. 



CHAPTER II. 



Chemical CojrarrrnnoN of Rocks and Soils • . . 38 



Different views taken of rocks by geologists, mineralogists and chemists ; farmer 

 takes only the chemical view ; nature of agricultural mineralogy ; farmer must 

 understand the results of the analysis of minerals ; division of the thirteen sub- 



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