Soluble vs. Insoluble Cane Manures. 333 
manures serving to supply nitrogen and phosphorus. 
Thus in the case of nitrogen, there are simple salts, such 
as sulphate and chloride of ammonium, and nitrate of 
potassium, sodium and ammonium ; and various nitro- 
genous animal matters as guano and other excreta, in- 
cluding stable and pen manure ; also prepared bones, 
blood, flesh, fish and offal, waste wool, hair, leather and 
horn, glue refuse &c; and numerous nitrogenous vege- 
table matters, chiefly the residual " cakes" left after 
expressing the oil from certain seeds, such as linseed, 
rape seed, cotton seed, poppy seed, sunflower seed 
sesame seed, coco and other palm nuts, earth nuts, 
&c. For supplying phosphorus, calcium phosphate (or 
phosphate of lime) is almost exclusively used, but va- 
rious forms of it can be obtained, e.g., ground bones, 
bone ash, steamed bone flour, spent animal charcoal 
or bone black, phosphatic or rock guano, coprolites (or 
the fossil excreta and bones of extinct animals), mine- 
ral phosphate such as apatite and phosphorite, also 
various kinds of chemically prepared or precipitated 
phosphate, and lastly and principally, " soluble" phos- 
phate or superphosphate of lime, made by treating 
bone-ash, mineral phosphate or phosphatic guano with 
sulphuric acid. The last substance is soluble in water 
whilst all the other phosphates enumerated are insoluble. 
Judging by the samples sent to the Government 
Laboratory for analysis, the manures that it is customary 
to use in British Guiana, are sulphate of ammonia to sup- 
ply nitrogen, and superphosphate of lime to supply 
phosphorus, or mixtures made up of those substances in 
certain proportions. Guano is also extensively employed, 
but principally the so called " dissolved" guano, which 
TT 2 
