Superphosphates Potash 85 



monia obtained in the manufacture of bone-black from 

 bones is identical with the ammonia obtained in the manu- 

 facture of illuminating gas or coke. In many cases, 

 doubtless, superior results have been obtained from the 

 use of the animal bone superphosphate, though this has 

 not been due to any inferiority of the available phosphoric 

 acid in the mineral superphosphate, but rather to the 

 fact that substances have been compared that are not 

 strictly comparable. They are radically different. The 

 one contains, in addition to its available phosphoric acid, 

 the only fertilizing ingredient in the mineral superphos- 

 phate, considerable nitrogen, and, moreover, it contains its 

 insoluble phosphoric acid in a form that is liable to decay 

 more rapidly than the insoluble in the mineral phosphate. 

 Soluble phosphoric acid is a definite compound. The 

 source from which it is derived does not influence this 

 point, and the action of a definite quantity is also identical 

 when conditions are similar. 



PHOSPHATES AND SUPERPHOSPHATES ARE NOT IDENTICAL 



The idea in the term "phosphate" should also be kept 

 distinct from that conveyed by the term "superphos- 

 phate." The first means, and should be applied to, any 

 material containing as its chief constituent phosphoric 

 acid ; the other means, and should be applied to, any 

 material containing soluble phosphoric acid as its chief 

 constitutent. The phosphates which have already been 

 described are each capable of being converted into a 

 superphosphate, as animal bone superphosphate, South 

 Carolina rock superphosphate, bone-black superphosphate, 

 bone-ash superphosphate, Florida rock superphosphate, 

 and Tennessee rock superphosphate. These superphos- 



