xvi TABLE OF CONTENTS. 



Origin of marl deposits 336 



Geographic distribution of marl deposits 339 



Physical characters of marl 340 



Chemical composition of marl 341 



Analyses of marls actually used 342 



Examining marl deposits 343 



List of references on marls 346 



CHAPTER XXVI. 



ALKALI WASTE: BLAST-FURNACE SLAG. 



Use of by-products as cement materials 348 



Alkali waste 348 



Leblanc process waste 348 



Ammonia process waste 349 



Analyses of alkali wastes 349 



List of references on alkali waste as a cement material 350 



Blast-furnace slag 350 



Slags in general 351 



Slags used as Portland cement materials 352 



CHAPTER XXVII. 



CLAYS, SHALES, AND SLATES. 



Relation of clays, shales, and slates 353 



Clays 353 



Origin of clays 353 



Composition of clays 354 



Clays used in cement manufacture . . . . 354 



Analyses of clays actually used. . . . 355 



Shales. . .' 357 



Origin and composition 358 



Analyses of shales used as cement material 358 



Examination of clay deposits 360 



List of references on clays and shales 360 



Slates 363 



Geographic distribution of slates 363 



Composition of slates 364 



Slates used in cement manufacture 365 



References on slates 366 



CHAPTER XXVIII. 



EXCAVATING THE RAW MATERIALS. 



Quarrying 367 



Stripping 368 



