550 PROCEEDINGS OP THE ACADEMY OF [Oct. : 



A QUICK METHOD OF TESTING FOE GOLD. 



BY E. GOLDSMITH. 



The volcan^r rocks of the crater in which the towns of Cripple 

 Creek and Jrictor, Colo., are built, according to Mr. Moore, the 

 chief mining engineer of the district, all contain gold. The rock 

 mined, however, is thrown on the dump and many thousands of 

 tons, n,6t worked for the gold at present, are piled up outside the 



The vein gold, in the form of sylyanite, telluride, and prob- 

 ably calaverite, is separated by hand from the gangue or rock and 

 sent to the smelters for reduction. A specimen was secured from 

 a depth of about 800 feet below the surface. Its general appear- 

 ance was^Trefr^ery promising, inasmuch as /me minerals were so 

 finely divided that a mechanical separation for a test seemed to 

 involve a waste of time. Separation, melting and cupellation are 

 practiced extensively and are well known. A quicker and simpler 

 method for at least a qualitative determination of the gold in the 

 rock can, 1 think, be devised. Sinjce these and other gold com- 

 pounds are very fusible, it seemed .probable that the small particles 

 of the gold salts may be fused together before the blowpipe in the 

 rock, and by shaking and drijftng with the pointed flame larger 

 globules may be formed. Tjiis proves to be the case. During 

 the process the tellurium and selenium, if present along with 

 other volatile bodies, are roasted, i. e., oxydized and expelled. The 

 flame is bluish green. After the volatile substances are thus 

 removed dark-colored glojbules project upward on the surface of 

 the rock -splinter, which was about one inch long and a quarter of 

 an inch thick. To clean these under the flame I covered the whole 

 surface with cyanide of potassium, a reducing fire finishing this 

 part of the work. V . ^^***\ 



The rock-splinter was disintegrated; it broke easily and the 

 globules of dark metal could be picked up with the pointed pin- 

 cette or separated with a knife. These were put into the agate 

 mortar and pressed and rubbed with the pistil to thin plates. A 



