20 MODERN HIGH FARMING. 



acid. No development of these plants took place, until he had made the 

 addition of phosphate of lime, when their growth became flourishing ! ! ! 



Meanwhile large workable deposits of mineral phosphates were 

 already known to exist, they having been simultaneously discovered 

 in their respective countries, by Buckland in England, and Berthier 

 in France ; and in the course of a lecture delivered to the British As- 

 sociation in 1845, Professor Henslow, describing the Suffolk copro- 

 lites, suggested the immense value of their application to agriculture. 



From this time may be dated the commencement of phosphate 

 mining, and it is certainly marvelous to contemplate, not only the 

 rapidity with which fresh deposits have been everywhere discovered 

 and opened up ; not only the millions of tons yearly raised to sup- 

 ply a never-failing demand, but also the fabulous amount of capital 

 and gigantic numbers of workmen constantly and remuneratively 

 employed in the production. 



Phosphates of lime have been found in rocks of all ages, and of 

 nearly every texture ; sometimes pure ; sometimes in different 

 forms of chemical combination ; in mineral fissure veins ; in pock- 

 ets, or filled-up cavities ; in stratified beds or layers, and in intimate 

 connection with the fossil remains and other phosphatic matter, de- 

 posited by the ancient seas. They are, however, chiefly found as: 



APATITES, or Crystalline Phosphates, occurring in the gneissic 

 rocks of the Laurentian age in North America and Norway, 

 and in the Silurian rocks of Spain and Portugal. 



COPROLITES, or Fossilized Nodules, occurring in the green sand- 

 stone, or cretaceous rocks of England, France, Belgium and 

 Russia. * 



PHOSPHORITES or Amorphous Rock Phosphates, occurring in 

 the Tertiary stratas principally in France, Germany, and 

 America (South Carolina). 



Their commercial value is entirely based upon their strength in tri- 

 calcic phosphate, which ranges in some regions and for some mar- 

 kets, from 30 per cent, up to 85 per cent. 



All those who are familiar with soil analysis will agree that, in 

 the majority of cases, the phosphates therein are found to exist as 



