52 
of East Flanders, which produces finer crops than 
any sand in Belgium with the least manure, con- 
tains only 13 per cent, alumina, 84 per cent, sand, 
and not a particle of lime."^ There are, in fact, 
several circumstances which modify the productive 
powers of soils, whatever their chemical constitution 
may be : for instance, alumina will absorb by cohesive 
attraction 2J times its weight of water ; lime its own 
weight; and silica J of its own weight; but although 
alumina has the greatest power of absorption, yet stiff 
clay soils do not take up so great a quantity of water 
as when mixed with a certain quantity of sand ; for clays 
in dry weather become indurated on the surface, which 
prevents absorption. A mixture of lime also prevents 
the cohesion of clays, and allows the ingress of moisture ; 
it is evident, therefore, that we cannot pronounce soils to 
be wet in proportion to the alumina which they contain. 
Again, if the soil be shallow, and the subsoil retentive 
of moisture, the soil itself, whether clayey or sandy, will 
be proportionably wet ; and here again chemical analysis 
would fail us. The state of division in which the sand 
exists also materially influences the fertility ; if the sand 
be in large quantity and coarse, the soil will be sure to 
be infertile, for when the sun comes upon it after rain, 
the particles cohere together like glass ; if in a minute 
state of division, the soil will be comparatively fertile. 
Mr. Tower's direction to form the best loam for horticul- 
tural purposes is 83 parts sand, nearly impalpable, and 
17 lime and clay, but, says he, if the sand be coarse, in 
hot weather after rain, the soil will set like mortar^ 
In fine. Professor Lowe says upon this subject, " It has 
" been found that the fertility of soils is not dependent on 
" the prevalence of any one mineral in the soil, but on 
"a mixture or combination of several. But what the 
♦ Farmers' Series : Flemish Husbandry. Page 10. 
