TABLE OR CONTENTS. 



Page. 



Letter of Transmittal. 



Preface 1 



I. GENERAL DISCUSSION OF CLAYS, BY HEINRICH RIES, PH. D 3 



Origin of Clay 3 



Geological Structure and Distribution of Clay Deposits 6 



Residual Clays 6 



Sedimentary Clays 7 



Distribution 8 



Properties of Clays 8 



Chemical Properties 9 



Alkalies in Clays 11 



Soluble Alkaline Compounds 11 



Insoluble Alkaline Compounds '. 12 



Iron Compounds in Clays 13 



Lime in Clays : 16 



Magnesia in Clays 19 



Silica in Clays 20 



Titanic Acid in Clays 21 



Organic Matter in Clays 22 



Water in Clays 22 



Moisture 23 



Combined Water 24 



Physical Properties of Clays 24 



Plasticity 25 



Tensile strength 26 



Shrinkage 26 



Fusibility of Clays 29 



The Thermo-Electric Pyrometer 31 



Segar Pyramids 32 



Chemical Effects of Heating 38 



Slaking 38 



Absorption 39 



Color of Unburned Clays 39 



Mineralogy of Clays 40 



Kaolinite 40 



Quartz 41 



Calcite 42 



Gypsum 42 



Mica 43 



Iron Oxide 43 



