FACTORS INFLUENCING THE ROUNDING OF SAND 



GRAINS 



VICTOR ZIEGLER 



South Dakota State School of Mines 



CONTENTS 



Introduction 



The Molecular Forces of Liquids 

 Molecular Forces and Transportation 

 Methods of Rounding 



Summary of Previous Work 



Experimental Work 



Summary 



INTRODUCTION 



In 1 910, while discussing the rounding of sand grains with 

 Professor A. W. Grabau, it seemed to the author that the influence 

 of viscosity was not sufficiently emphasized in the literature on 

 that subject. Subsequent discussion with Professor C. P. Berkey 

 suggested this investigation. The thanks of the author are due to 

 Professor James F. Kemp, and especially to Professor C. P. Berkey 

 for many kind and valuable suggestions. 



THE MOLECULAR FORCES OF LIQUIDS 



For a clear understanding of the forces acting on a particle 

 submerged in water it is necessary that we review briefly a few of 

 the elementary definitions of physics. This can most clearly be 

 done by means of an illustration. 



If we look carefully at the surface of a glass of water, we notice 

 that it is not horizontal but curves upward at the sides of the con- 

 taining vessel as though attracted by it. If we dip a clean glass 

 rod in water and remove it, we shall see adhering to it a thin film 

 of water. Upon slightly shaking the rod this film will be dis- 



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