CHAPTER IV. 



PHOSPHATES DISCOVERY OF THEIR ACTIVE PRINCIPLE USE 



OF BONE MANURE DISCOVERY OF MINERAL PHOSPHATES 



HOW THEY OCCUR IN NATURE THEIR FORM IN THE 



SOIL HOW THEY ARE MADE SOLUBLE HOW THEY ARE 



ASSIMILATED BY PLANTS MIGRATIONS OF PHOSPHORUS 



THE NECESSITY FOR ARTIFICIALLY INTRODUCING PHOS- 

 PHORIC ACID AS MANURE. 



Of the absolute necessity for the presence in the soil of such min- 

 erals as phosphorus, potassium and lime, we have the most undeni- 

 able proofs ; for it has been clearly shown that vegetables, though 

 abundantly supplied with oxygen, hydrogen, carbon, and nitrogen, 

 remained puny and devoid of vigor if deprived of mineral salts. 



The form in which phosphorus is assimilated is that of phosphate 

 produced, first by the action of oxygen as phosphoric acid, and then 

 by the combination of this acid with various bases, the principal of 

 which is lime. Enormous deposits of phosphate of lime have been 

 and doubtless will continue to be discovered in every quarter of the 

 globe; and as, besides being an essential to plant life, it is the princi- 

 pal constituent of bones, we may assume that, if by some extraordi- 

 nary phenomenon its source were suddenly cut oft' or exhausted, all 

 vegetable and animal life would come to an end. 



So far back as the year 1698 a celebrated French engineer Van- 

 ban writing in the Dime Royal, says : 



"We have for a long time past been universally complaining of 

 the falling off in the quantity and quality of our crops ; our 

 farms are no longer giving us the returns we were accustomed to ; 



