ic acid in the commoner rocks 211

CHAPTER VI.--POSITION OF POTASH IN AGRICULTURE.

Potash of less importance than phosphoric acid 212
Occurrence of potash 213
Felspar and other potash minerals 213
Stassfurt salts 214
Occurrence of saltpetre 215
Occurrence of potash in the soil 215
Potash chiefly in insoluble condition in soils 216
Percentage of potash in plants and plant-ash 216
Occurrence of potash in animal tissue 217
Sources of loss of potash 217
Amount of potash removed in crops 218
Amount of potash removed in milk 218
Potash manures 218

APPENDIX TO CHAPTER VI.
NOTE
I. Amount of potash in different minerals 220
II. Quantity of potash obtained from 1000 lb. of different
kinds of vegetation in the manufacture of potashes 220

PART III.--MANURES.

CHAPTER VII.--FARMYARD MANURE.

Variation in its composition 223
Made up of three classes of constituents 224
_Solid excreta_--
Its nature 224
Difference in composition of the solid excreta of the
different farm animals 224
Causes of this difference 225
Percentage of manurial ingredients in solid excreta
of different animals 226
_Urine_--
Its nature 228
Variation in its composition 229
Causes of this variation 229
Manurial value of the urine of the different farm
animals 230
Percentage of the _orga