Cane Soils and Artificial Manures. 291 
ill effects of the kind would follow its use, provided no 
great quantity were employed. At all events the matter 
is well worth the test of experiment ; and trials might be 
made on a small scale, by applying the salt in the propor- 
tion of from two to three hundred-weights per acre to 
soils known to be deficient in chlorine. 
Sulphuric acid is contained in sulphate of ammonia 
and in superphosphate of lime ; and doubtless when those 
substances are used as manures, the sulphuric acid often 
shares in producing the beneficial effects usually attribu- 
ted to the ammonia and phosphoric acid. It is even 
probable that the ascertained superiority of superphos- 
phate over insoluble phosphate depends more upon the 
existence of sulphuric acid in the former compound than 
upon its mere solubility ; especially as there is reason 
to believe that superphosphate is speedily converted into 
insoluble, and almost inert, phosphate of iron and alum- 
ina when mixed with the clay soils of this colony. 
One of the cheapest manurial substances containing 
sulphuric acid is selenite or gypsum, a hydrated sulphate 
of lime which is found native in immense quantities and 
consists of : — 
Sulphuric Acid ... ... ... __ 46 - 51 
Lime 
32-56 
Water 20-93 
10000 
In fine powder and in a partially dehydrated state it can 
be bought in England for fifteen or sixteen shillings a ton. 
It serves to supply lime as well as sulphuric acid, and 
might in many cases advantageously replace a portion 
of the slacked lime so extensively employed in cane 
