424 



INDEX 



Chromic acid, and combustion 

 methods, comparison, or- 

 ganic matter, 155 

 method of determination of 



organic matter, 154 

 Churn elutriator, physical analysis, 



Hilgard, 126 



Cippoletti or trapezoidal weir, 209 

 Classes, types and phases, in Illi- 

 nois, 114 

 Clay, defined, 134 

 dunes, 53 



effect of, on shrinkage, 133-135 

 loams, 115 

 tight, 68 

 Clays, 114 



and clay loams, properties of 

 coagulation or floccu- 

 lation, 137 

 plasticity, 135 

 puddling, 136 

 shrinkage, 135 

 tenacity, 134 

 Clark, F. W., composition of known 



earth, 2 

 Classification of soils, by Bureau of 



Soils, chapter on, 78 

 based on color, 77 

 geology, 72 

 lithology, the parent 



rock, 73 

 moisture, 73 

 temperature, 73 

 texture, 77 

 vegetation, 75 

 need of, 72 

 Cleavage, vertical, characteristic of 



deep loess, o3, 64 

 Coagulation or flocculation of clays, 



137 



Coal, formation of, from organic mat- 

 ter, 146 

 Coffey, G. N., dark color indicating 



outcrop of limestone, 177 

 lime and magnesia in soils, 75 

 mineral content of soils, 74 

 reports clay dunes in Texas, 53 

 soluble salts in soils, 74 

 Colloids, affecting hygroscopic moist- 

 ure, 195 



dialysis and diffusion of, 131 

 examples of, 129 

 in soils, 132 



organic and mineral, 132 

 properties of, 130 

 adsorption, 132 



Colloids, properties of, boiling point, 



effect on, 131 



Urownian movement, 130 

 dialysis, 130 

 diffusion, 130 

 electrical behavior, 131 

 freezing point, effect on, 131 

 shrinkage, 132 

 size of particles, 130 

 Colluvial soils, 30 

 Color of soils, 176 



changed by erosion, 361 

 effect of deoxidation on, 21 

 on temperature, 303 



of sands, 302 



factor in classification, 77 

 Colorado mud-flow, 34 

 river, work of, 17 



Grand Canon, 17 

 Columbia glacier, over-riding forest, 



Alaska, 14 

 front of, 15 

 Columnar arrangement of particles, 



180 



Combustion and chromic acid 

 methods, comparison, organic 

 matter, 155 



in oxygen determination of or- 

 ganic matter, 154 

 Compacters, bar roller, 337 

 corrugated roller, 336 

 cultipacker, 336 

 drum roller, 335 

 plankers, 337 

 subsurface packer, 337 

 Compacting the soil, a part of till- 

 age, 326 

 increases moisture capacity, 



230 



Composition of feldspars, 3 

 fresh manure, 163 

 known earth, 2 

 river sediments, 262 

 Concrete dams for filling gullies, 373 

 Concretions, calcium carbonate, 63 



iron, 64 

 Conductivity of soil, effect of, on 



temperature, 306 

 material, 306 



Constituents of soils, mineral, chap- 

 ter on, 123 



organic, chapter on, 142 

 Contour plowing, deep, aid in check- 

 ing erosion, 364 



seeding, aid in checking erosion, 

 365 



