g place 385
Phosphates of lime 385
Reverted phosphate 389
Value of reverted phosphate 391
Composition of superphosphates 391
Action of superphosphates 392
Action of superphosphate sometimes unfavourable 395
Application of superphosphate 395
Value of insoluble phosphates 396
Rate at which superphosphate is applied 397

APPENDIX TO CHAPTER XIII.
NOTE
I. The formulae, and molecular and percentage composition,
of the different phosphates 398
II. Reactions of sulphuric acid and phosphate of lime 398
III. Table for conversion of soluble phosphate into insoluble
phosphate 399
IV. Action of iron and alumina in causing reversion 399
V. Relative trade values of phosphoric acid in different
manures 400

CHAPTER XIV.--THOMAS-PHOSPHATE OR BASIC SLAG.

Its manufacture 401
Not at first used 403
Discovery of its value as a manure 403
Composition of basic slag 404
Processes for preparing slag 406
Solubility of basic slag 408
Darmstadt experiments with basic slag 410
Results of other experiments 413
Soils most suited for slag 414
Rate of application 414
Method of application 416

APPENDIX TO CHAPTER XIV.

Analysis of basic slag 417

CHAPTER XV.--POTASSIC MANURES.

Relative importance