UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 4, No. 11, pp. 201-226, Pis. 26-27 Andrew c. lawson, Editor 



THE DIFFERENTIAL THERMAL CONDUC- 

 TIVITIES OF CERTAIN SCHISTS. 



BY 



Paul Thelen. 



CONTENTS. 



page 



Introduction 201 



The Use of the Wax-figure for the Determination of Eelative Heat- 

 Conductivities 205 



Methods used by the Writer 211 



The Conventions used in speaking of the Schists 215 



The Bocks Investigated and the Results Obtained 216 



Petrography of the Schists 218 



The Hornblende Schist 218 



The Glaucophane Schist 221 



The Quartzose Schist 222 



The Wrangell Mica Schist 224 



INTRODUCTION. 



We know that in general the physical properties of crystalline 

 substances are functions of direction, that is, crystallographic- 

 ally similar directions show like physical properties (conduc- 

 tivity for heat, light, and electricity, dilatation, cleavage, hard- 

 ness, solubility, etc.), while crystallographically dissimilar 

 directions may show unlike properties. Even isotropic sub- 

 stances, for instance, possess cleavage. Here the behavior toward 

 light is the same in all directions, while the cohesion is not. 

 These phenomena, observed in all crystalline bodies, are referred 

 back to an internal molecular structure. This structure is sug- 

 gested to us, too, by the external geometrical form of the 

 crystals. 



