286 TlMEHRI. 
tween a good and a bad cane soil principally depends 
on its power of readily supplying the cane with less than 
a half of one per cent, of mineral substances. Leaving 
out of the question nitrogen, which, like carbon dioxide 
and water, may be regarded as more or less an aerial 
plant-food, let us confine ourselves to the strictly mineral 
substances that the cane assimilates from the soil. By 
burning a known quantity of cane, and weighing the ash 
obtained, the gross amount of mineral matter is de- 
termined ; and by submitting this ash to a quantitative 
analysis the nature and proportion of its constituents is 
readily ascertained. The following table shows the mean 
percentage composition of the ash, calculated from the 
analyses by Dr. STENHOUSE, of twelve samples of sugar- 
cane from Trinidad, British Guiana, Grenada and Ja- 
maica (i), and also of the ash of a ripe cane with its 
leaves, given by Dr. Phipson (2). 
I. II. 
Potassa 
19-70 
18 00 
Soda 
336 
2-00 
Lime 
8-71 
1000 
Magnesia ... 
7-62 
6-50 
Sulphuric acid 
6-62 
8-00 
Phosphoric acid 
6-81 
6-00 
Chlorine ... 
562 
4-50 
Silicic acid.. 
43-15 
43-00 
Oxide of iron niaganese &c... 
— 
2-00 
101-59 
100-00 
Deduct oxygen... 
1-26 
10033 
Presuming then that the cane yields 0*48 per cent, of 
mineral matter of the above composition, it follows that 
a crop of say 30 tons to the acre would remove from that 
extent of soil 344*56 pounds, or nearly three hundred 
