324 ’ THE ATLANTIC. (CHAP. Iv. 
decomposable part, and that which would have been soluble in dilute 
hydrochloric acid after the acetic solution. 
The considerable quantities of alumina dissolved both by weak and 
strong acids shows all the soils to be readily acted on by weather, and 
consequently having a proportionate facility for renewing their fertility. 
This is especially the case with No. 3 soil. There is no marked defi- 
ciency of any normal constituent in any of the soils, with the exception 
of chlorine and sulphuric acid. In No.1 soil both are nearly absent; 
in soil No. 2 the chlorine is a mere trace, and in soil No. 5 the sulphu- 
ric acid is very minute. The actual weight of these minute quantities, 
however, when multiphed up to that actually existing in an acre of soil 
one foot deep, is, as has been shown by Professor Way, not at all insig- 
nificant. 
Phosphoric acid is present in soil Nos. 1, 2, 3 in unusually large 
quantities, the average for a fertile soil being 0°10 per cent. With cer- 
tain limitations, it is scarcely fair, when all the constituents of a soil are 
essential to the proper development of plants, to attach a higher impor- 
tance to one than to another; some, however, are invariably present in 
large quantities, and seem to serve more as a medium of growth than 
by any chemical activity; some constituents are more easily and cheaply 
supplied than others; the direct application of some to an appropriate 
crop producing a corresponding increase in yield, when a supply of 
others would produce no increase. 
The large amount of phosphoric acid in the three soils (Nos. 1, 2, 3), 
should, by disintegration and proper cultivation, maintain their fertility 
for ages to come, and the coral and chalk (Nos. 4, 5) will furnish excel- 
lent dressings for clay sands where there is a deficiency of lime. 
To maintain the fertility of a soil under proper cultivation, it is nec- 
essary to supply in the manure the minerals which are taken off in the 
crop. It by no means follows that the constituents of a crop form the 
best fertilizers for that crop; in fact, the contrary statement seems to 
hold good—the special manure for some crops is just that constituent 
in which they are deficient. The wheat crop, for instance, which is 
starchy rather than nitrogenous, is greatly increased by the direct appli- 
cation of nitrogenous manures. The same may be said of the sugar- 
cane, and, I have little doubt, of arrowroot. In the case of wheat, the 
increase in the crop by the nitrogenous manures may be calculated 
within narrow limits; but, if supplied to a bean crop, not only no ben- 
efit is found, but in some cases positive injury. Green crops of all 
