Xii TABLE OF CONTENTS. 



PAGE 



General discussion 201 



Georgia 202 



Illinois 203 



Indiana-Kentucky 204 



Kansas : , 205 



Maryland 205 



Minnesota 205 



New York 207 



North Dakota 210 



Ohio 210 



Pennsylvania 210 



Texas 211 



Virginia 212 



West Virginia-Maryland 213 



Wisconsin 213 



European natural-cement rocks 214 



General characters and subgroups 214 



Natural Portlands 214 



Roman cements 214 



Natural-cement materials of Belgium 21 5 



Natural-cement materials of England 217 



Excavation of natural-cement rock 219 



Methods 219 



Costs 220 



References on natural-cement rock 221 



CHAPTER XVIII. 



MANUFACTURE OF NATURAL CEMENTS. 



Processes of manufacture 223 



Burning practice and theory 223 



Chemical changes during burning 223 



Relation of composition to degree of burning 224 



Losses in burning 224 



Types of kiln used 225 



Fuel consumption in burning natural cement 233 



Hard and soft clinker 234 



Seasoning and slaking 235 



Grinding the clinker 236 



General practice 236 



Actual mill equipments of American plants 237 



Types of grinding machinery employed 238 



Jaw crushers 238 



Cone grinders: crackers 238 



Rolls 239 



Millstones . 239< 



