THE SOIL OP THE COTTON STATES. 69 
consisting of the mineral salts which were combined with 
the above-named acids. The organic acids weigh 9^ 
grains, or ninety-two hundredths of one per cent., and the 
ashes, or mineral salts, eight-hundredths of one per cent. 
' One hundred grains of the subsoil yield on analysis — 
Silica 90.000 per cent. 
Alumina 2.000 " 
Lime 0.280 " 
Magnesia 0.300 " 
Potash 0.290 " 
Soda 2.014 " 
Peroxides of iron and manganese. 1.200 " 
Phosphoric acid 0.800 " 
Sulphuric acid O.OOT " 
Chlorine 0.005 " 
Orenic, apocrenic, and humic acids . 1.020 " 
Insoluble vegetable matter 2.Y90 " 
100.716 
One thousand grains of this subsoil, on digestion with 
a solution of carbonate of ammonia, at a boiling heat, 
yield 1 2^ grains of soluble organic matter and salts ; and, 
on combustion, two grains of saline or mineral matter re- 
main, leaving for organic matters dissolved 12^ grains. 
The ash contains phosphate of hme, sulphate of lime, soda, 
potash, and chlorine. 
From the composition of this subsoil, it will appear 
that deep or subsoil ploughing is indicated as appropriate 
for this plantation ; for the subsoil is richer in certain im- 
portant ingredients than the surface soil, as will be seen 
on comparing the proportions of soda and of phosphoric 
acid. 
