E. W. Hilgard— Objects and Interpretation of Soil Analyses. 198 
unequivocally in the tree-growth, the lime-percentage should 
not fall below 0°100 in the lightest sandy soils; in clay loams 
not below a fourth of one per cent, 0°250; and in heavy clay 
soils, not below 0°500, and mo advantageously rise to one and 
even two per cent. Beyond t er figure, it seems in no case 
to act more favorably than a i mir unless it be mechani- 
cally 
The effect produced by the presence of such, or greater per 
centages of lime in the soils seems to be a kind of ‘ * anfechlies- 
sung,’ an energizing or rendering active of that which otherwise 
would remain inactive. This becomes evident at once in the 
smaller insoluble residues from the acid treatment, yielded by 
such soils; there being then oftentimes a complete dissolution 
of the alumina, a ey part of which ordinarily remains behind 
in the shape of clay (kaolinite-particles). It would seem that 
as regards the silicates, the carbonate of lime in soils performs 
in a measure, the same functions as the caustic lime in Law- 
rence Smith’s method of silicate ‘‘aufschiiessung.” We have 
an indication of the same action in the case of marls, whose 
small percentages of potash and phosphates act so energetically, 
and in which we so often find the potash in the highly availa- 
ble form of glauconite grains; also in the er Sate of 
potash from zeolitic compounds, by lime or lime sa 
rom the evidence before me, I should specify as follows, 
the advantages resulting from the presence of an adequate 
supply of lime in soils: 
more rapid transformation of vegetable matter into 
distioe humus which manifests itself by a dark, or deep black 
tint of the soil. 
he retention of such humus, against the oxidizing influ- 
ences of hot climates ; witness the high humus-percentages of 
such soils, as against all others, in the Southern States. 
c. Whether through the medium of this humus, or in a more 
direct manner, it renders adequate for profitable culture per- 
centages of phosphoric acid and potash so small that, in the case 
of deficiency or absence of lime, the soil is practically sterile. 
d. It tends to secure the proper maintenance of the condi- 
tions of nitrification, whereby the inert nitrogen of the soil is 
rendered available. 
e. It exerts a most important physical action on the floccula- 
tion, and therefore on the tillability of the soil, as heretofore 
shown by Schloesing and by myself. 
I may add that in 1 the pont majority of soils (excepting those 
that are extremely sandy) the lime-percentage is greater in the 
subsoil than in the surface soil. This is, doubtless, the result 
of the easy solubility of calcic carbonate in the soil water 
which carries it downward and thus tends to deplete the sur- 
