POTASSIC MANURES. 129 



phosphate is alkaline, hence, if mixed with sul- 

 phate of ammonia it will liberate the ammonia. 

 For this reason it must not, when used as 

 a manure, be put on with sulphate of ammonia 

 but if these two substances are to be applied 

 to the same piece of ground the basic phos- 

 phate should be put on first and worked into 

 the soil, and, some weeks later, the sulphate of 

 ammonia should be added. 



POTASSIC MANURES. 



1. Kainit. A mineral obtained from the 

 Stassfurt mines in Germany. It consists of sul- 

 phate of potash together with common salt and 

 Epsom salts. The actual amount of potash 

 contained is usually about 12 per cent. On 

 calcareous soils, such as those of Barbados, 

 potash gives very good results. 



2. Sulphate of potash. This is really a 

 purer form of kainit, containing about 50 per 

 cent, of potash. 



PKACTICAL WORK. 



Burn some vegetable matter, for instance 

 leaves or twigs on a sheet of iron over a fire, or 

 some wood in a coal-pot. Notice that a large 



