i9« 



The Canadian Horticulturist. 



used by the analysts of the Eastern 

 States during the present year : 



Ph. Acid — Soluble in water, 8cts. p. lb 



" Reverted form, 'j\ " 



" Fish, fine bone, 7 " 



" Fine med. bone, 6 " 



" Medium bone, 5 " 



" Coarser bone, 4 " 



" Fine gr. r'k ph. 2 " 



A value is thus arrived at by con' 

 sidering the solubility, the size of 

 particles, and the source. 



Let us next distinguish between 

 soluble, reverted or partially soluble, 

 and soluble phosphates. We shall 

 take the different phosphates of lime. 

 The relationship of the various forms 

 can be most easily seen from the 

 following arrangement : 



Pure Acid. Soluble Phosphate. 

 Water) Water | 



Water' Ph. Acid. Water -Ph. Acid. 

 Water! Lime j 



Insoluble Phos. 

 Limel 



Reverted Phos. 



Water] 



Lime -Ph. Acid. Lime |-Ph Acid 



Lime J LimeJ 



Or, in chemical notation : 



H2O] 



H20^P205 



C20 



CaO] 

 C,0[P205 



c, o 



phosphate in simple form as follows: 



I W' ater. | Lime j 



2 -Sulphuric^ + Lime -Ph. Acid = 

 i [Acid.) Lime) 



Water) 1 Lime. \ 



Water -Ph. Acid. + 2 - Sulphuric [ 

 Lime ) ( [Acid. I 



H-iOj 



H2O 'P2O5 

 H20J 



H2OI 

 CaO -P2O5 



c^oj 



The change from the pure acid to 

 the insoluble form is a removal of 

 water and an introduction of lime. 

 In our rock phosphate, and in bones, 

 the form is that of the insoluble 

 phosphate. The treatment by sul- 

 phuric acid changes this, more or 

 less, into soluble phosphate, the lime 

 that is removed being changed into 

 sulphate of lime or gypsum. Super- 

 phosphate thus made, therefore, con- 

 sists of soluble phosphate, gypsum, 

 and variable quantities of the other 

 two phosphates. 



In harmony with the above, we can 

 represent the formation of super- 



Or, in chemical notation 



o, 



c, o 



fc, o [ 



|S O3 J 



Sulphuric acid and insoluble phos- 

 phate of lime react on each other, 

 forming soluble phosphate of lime 

 and sulphate of lime or gypsum. 



Bone superphosphate, or dissolved 

 bone, is considered more valuable 

 than mineral or rock superphosphate. 

 The mixing of lime with superphos- 

 phate tends to change the soluble 

 phosphate back to the less soluble 

 form, the reverted. Decaying organic 

 matter, whether in a compost heap 

 or in a soil, will have the effect, to a 

 small extent, of changing the in- 

 soluble forms to soluble. 



Phosphates are of most service 

 with organic fertilizers on black 

 humus soils, along with farm-yard 

 manure or nitrogenous fertilizers, and 

 are of less benefit in connection with 

 lime. 



Phosphatic fertilizers give good 

 results when applied to pastures, 

 cereals and roots, especially turnips. 



SOURCES. 



I. Farm-yard manure contains 

 from 0.15 to 0.75 per cent, of this 

 acid, having an average of about 

 0.50 per cent., or 10 lbs. to the ton. 

 Poultry droppings hive about four 

 times as much. 



II. Ashes (fresh and leached) have 

 from -I to i\ lbs. per bushel. 



III. Fresh bones (sold as crushed 

 bone, bone meal, or float bone, 

 according to texture) should contain 



