CONTENTS V 



Platinum. 



BY David T. Day 297 



Graphite. 



BY Joseph Struthers 300 



Clay. 



BY Jefferson Middleton 312 



Crude Mineral Pigments. 



BY Joseph Struthers 317 



Precious Stones. 



BY George F. Kunz 324 



Sulphur and Pyrite. 



BY Joseph Struthers 348 



Mica. 



BY Joseph Hyde Pratt » 3G1 



Petroleum. 



BY F. H. Oliphant 366 



Njtural Gas. 



BY F. II. Oliphant 380 



Aspjaltum and Bituminous Rock. 



BY Joseph Struthers 395 



GypsuP- 



BY Story B. Ladd 407 



Borax. 



BY Joseph Struthers 414 



Talc and Soapstone. 



j^\ Joseph Hyde Pratt 424 



Abrasive Materials. 



pY Joseph H'i'DE Pratt 430 



Phosphate f^ock. 



RY Joseph Struthers 438 



Barytes. 



BY Joseph Hyde Pratt 443 



Mechanical ;^"d Engineering Progress as Influenced by the Mining 



Industry- 



BY John Birkinbine 446 



