[249] The amount of "reverted" phosphate is estimated by the ammonium citrate process.
[250] See Note I., p. 553.
[251] See Note II., p. 554.
[252] See Note III., p. 556.
[253] See Chapter on Farmyard Manure, p. 271.
[254] See Note IV., p. 557.
[255] See Chapter on Farmyard Manure, pp. 224-236.