68 MANUAL FOR SUGAR GROWERS. 



often employed as a manure, is carnallite. This 

 contains chloride or muriate of potash and chloride 

 of magnesia. It is found, however, that it is pref- 

 erable to employ potash salts in the form of sul- 

 phate rather than chloride, hence carnallite is not 

 a manure likely to attract the attention of sugar- 

 cane growers. Amongst the manures obtainable 

 locally, wood ashes, leaves, etc., and urine are rich in 

 potash, and should on no account be wasted. 



Practically, then, the best form of potash manure 

 to import is the sulphate ; this can now be obtained 

 of a very high degree of purity. A guarantee as to 

 the amount of potash it contains should always be 

 required. 



Phosphatic Manures. The first phosphatic ma- 

 nure employed was bones, and bones are used at the 

 present time when it is necessary to employ a phos- 

 phatic manure whose action shall extend over a 

 long period. Raw bones contain about forty to fifty 

 per cent, of phosphate of lime, and if they have 

 been steamed or boiled to remove the gelatine, the 

 quantity of phosphate of lime is raised to about sixty 

 per cent., while the nitrogen, of which there is about 

 four per cent, in raw bones, is reduced to about one- 

 fifth per cent. Bones being very insoluble and thus 

 requiring a very long time for their disintegration, 

 a method was devised by Liebig by which they 

 could be rendered soluble and so caused to act more 

 quickly. He suggested the treatment of the bones 

 with sulphuric acid. By this means an acid phos- 

 phate of lime is formed, together with sulphate of 

 lime, or gypsum, and this in a little time forms 



