XLV HOW CROPS FEED. 
Kocks, conversion into suils........ 122 
Koots, direct action on soil........ 326 
Saline incrustations.............66+ 179 
Saltpeter......... 
Salts decomposed or absorbed by 
the soil 
SETI sie eavecaie's 
Sand filter... 
Sandstone... 
Serpentine........ 
Schist, micaceous, 
“ talcose.... 
te chlorite. 
Shales. . 
Sherry wine rezior 
Shrinking of soils.. 
N, 
“function in the soi 
“ of soil, liberated by strong 
tas 
Silk, hygroscopic ifs acinar 
Soapstone...... 0... cece rene ee 
Sod, temperature of 
* absorptive power of.... 
* aid to oxidation........ 
‘+ aqueous solution of. 
‘* condenses gases.... 
“ capacity for heat.. 
* chemical action in.. 
* composition of.... 
* exhaustion of..... 
© inett DASTB eeccae 
“ natural strength of... 
* origin and formation. “106, 122, 135 
“ physical characters...........-- 157 
** porosity Of........... 
* portion insoluble in acids 3 
“ relative value of ingredicnts... .367 
* reversion to rock............06+ 32 
* solubility in acids. . 
* source of food to crops. . 
‘* state of division...... ......... 
Soils, sedentary.............0005 
‘*  transported.. 
“weight of.. 
Solubility, standards of............308 
Solution of soil in acids........ 
“ a ‘* water, . . 
Stentite.........cce cece eee eeee ence 
Swamp muck 
Sulphates, agents of oxidation..... 258 
Sulphate of lime.... 
Sn)phur, in decay. 
Sulpburous acid. . 
Sulphydric acid .. 
Temperature of soil 
Transpiration 
Trap rock...... 
Ulmates........ -- 
Ulmic acid... . - -224, 226, 229 
224, 226, 229 
ULC vac eeeie ces + 294, 27% 
Uric acid 295, 27% 
AM Glnx.zivid exeesreseuisciaaeiert stustnnalaaae 293 
preserved fresh by clay....... 293 
its nitrogenous principles as- 
7 similated by plants. 
Vegetation, antiquity of........ 
‘e decay Of..........4. aa 
ae action on soil........ 140 
Volcanic rocks, conversion to soil. .135 
Wall fruits... 0.20000 scence ee eee 199 
Water absorbed by roots....... 202, 210 
“functions of, in nutrition of 
Plate, cocci cscs ewe 216 
“© imbibed by soil....... .. ....180 
“movements in soil.... ..... 1% 
“proportion of in plant, infiu- 
enced by soil............. 
Be OR BON sce: ce crceiee averse 
‘ “bottom water. : 
© caplllaryccc cewee saaieness 
te hydrostatic..........-02 eee 199 
“ Iygroscopic... . ...-.-2-5-- 201 
‘* quantity favorable to crops. .214 
Water-currents..........66 cece eee 124 
Water-vapor, absorbed by soil.161, 164 
exhaled by plants.... 99 
Ey not absorbed by 
plants......... 35, 99 
i of the atmosphere.... 34 
Weathering..............00008: 131-134 
Wilting... ... 
Wool, hygroscopic. 
Zeolites......ccceceessceseveeeedl4, 349 
