CONTENTS. 



Page 

 Introduction 1 



CHAPTER I. 



On the Polarity of the Earth's Magnetism 3 



CHAPTER II. 



The Identity of Magnetic and Galvanic Currents 15 



CHAPTER III. 



On the Reduction of Metals by Electro-Magnetism or Galvanic 

 Currents . 17 



CHAPTER IV. 

 On Heat produced by the Magnetic or Galvanic Fluid 23 



CHAPTER V. 



Terrestrial Magnetism, or the Effects of the Positive and Nega- 

 tive Poles of the Globe on all Substances within the limits of 

 their actions. — Cleavage Planes, &c 28 



CHAPTER VI. 



On the General Character of the Crystalline Rocks called " Pri- 

 mary." — Granite, Gneiss, Schist, &c 35 



CHAPTER VII. 



On the Order of the Splits, Fractures and Dislocations in the 

 Primary Rocks, including the Superincumbent Sedimentary 

 Masses. — Heaves, Slides, &c 43 



CHAPTER VIII. 



Mineral Veins, their Mode of Filling, and the General Character 



of their Contents. — Roots and Branches of Mineral Veins The 



Influence of the Impermeable Splits on the Accumulation of Mi- 

 nerals in the Transverse Fractures. — Recapitulation 47 



