Manures and the principles of manuring

by Charles Morton Aikman

APPENDIX TO CHAPTER XIII.

NOTE I. (p. 388).

The formulæ, and molecular and percentage composition, of the different phosphates, are given in the following table:—

		Composition in terms of—
		Molecular weight.				Per cent.
Name.	Symbol.	Lime.	Water.	Phosphoric acid.	Total.	Lime.	Water.	Phosphoric acid.
Tri- or bone-phosphate.	3CaO, P2O5	168	0	142	310	54.19	0.00	45.81
Bi- or di-phosphate.	2CaO, H2O5	112	18	142	272	41.18	6.61	52.21
Mono- or super-phosphate.	CaO, 2H2O, P2O5	56	36	142	234	23.93	15.39	60.68

NOTE II. (p. 388).

When sulphuric acid is added to tricalcic phosphate, the following reaction takes place:—

(1.)	3CaO, P2O5	+	2(H2O, SO3)
	(Tricalcic phosphate),		(Sulphuric acid),
=	2(CaO, SO3)	+	CaO, 2H2O, P2O5
	(Gypsum)		(Monocalcic phosphate).

(2.) 3CaO, P₂O₅ + 3(H₂O, SO₃) = 3CaO, SO₃ + 3H₂O, P₂O₅, or 2H₃PO₄.

NOTE III. (p. 390).

This equation gives the chemical reaction taking place when soluble phosphate is reverted, owing to the presence of undissolved phosphate:——