PHOSPHORIC ACID3. 



This element of plant food exists in the various manurial sub- 

 stances, combined either with water alone or with lime in one of 

 four different proportions. Such combinations, their ajqiroximate 

 relative solubility, and their occurrence, may be briefly described as 

 follows : — 



COMPOUNDS OF PHOSPHORIC ACID^ AND LIME. 



Composition Name Soluble in Occurs in 



1 



r- 1 Three-lime Acid. Very slow- Bones, 



J. ', p, A • -1 phosphate ly in soil waters. Mineral 



T- • or bone- phosphates. 



Lime 7 7, 



J phosphate. 



(i.e. .3 parts of lime with 1 part acid.) 



2 



J- . ^ Two-lime Citrate of am- Sii2)erphos- 



j. ! p. , A 'i phosphate monia. Soil X)hates, etc. 



,y- ,' '■ orReverted water- ho 1 d i n g ^'Di s solv ed 



J phosp)hate. carbonic acid. hone-meals." 



(1. 6. 2 parts of lime to 1 part acid.) 



3 



y . ) One-l im e 



Water i>Phos.Acid ^'^'^f^J^// Water .^''P^- 



,,,- . I or '■'• soluble phosphates. 



Water ? 7 , >> 



j phosphate 



(i. e. 1 part of lime to 1 part of acid.) 

 4 



Water ) pi j .-, Certain very 



Water V Phos.Acid . .' ^ Water high grade 



Water ) ' phosphates. 



(i. e.3 parts of water to 1 part acid.) 



5 



Lime "^ 



Lime ! p, . . ■, Four-lime Phosphatic 



mie j phosphate slag. 



Lime J 



(i. e. 4 parts of lime to 1 part acid.) 



Superphosphates, dissolved bone- meals and other manufactured 

 products may contain phosphoric acid in all of the first three forms. 



It should be remembered that the above j^ar^s- are not by weight, 

 but by bullv. One part by buliv of lime weighs oT) pounds, one part 

 by bulk of phosphoric acid^ weighs 142 pounds. 



Lime, lbs. Plios. Acid, lbs. Lbs. 



168 combine with 142 to form .iio three-lime phosphate. 



112 " " 142" " 2r)l two-lime 



66 " " li2 " " 198 one-lime 



