INSTl;lMI.\T> AM) ( I1I..MK \l. Ti - 581 



moistened with a drop of IK 'I ; heated oner more in a -mall l{. I 1 '., 



I a l>ritfht a/ure-Mue copper chloride llame will appear, which on 

 IOIIL; heating, if much copper is piv-nit, will give way to the ^reen 

 llame of copper oxide. The a/ure-l>lue flame with care will detect 

 .1 per cent, of copper. 

 b. Bead test. Oxide of copper when dissolved in borax 

 yields in O. F. a green bead while hot, becoming blue when cold. 



Iln K. F., if it contains much oxide, the bead is opaque red when 

 cold, due to cuprous oxide, Cu 2 O; if the reduction is continued, 

 the cuprous oxide is reduced to metallic copper and the borax is 

 colorless, especially if reduced on coal. In S. Ph. the colors are 

 the same as in borax, 

 c. Reduction test. Copper is reduced from its oxidized 

 compounds with soda and borax in R. F. on coal, yielding red 

 buttons and scales of malleable metal on washing the charge in 

 the mortar. Sulphides and ores containing arsenic and antimony 

 should be roasted before mixing with soda. 



Illustration. Powder some chalcopyrite, spread it out in a 



I thin layer on coal, and heat it with an O. F., but do not fuse it; 

 turn it over and continue the roasting until the odor of SO 2 has 

 disappeared. Allow it to cool and moisten with a drop of HC1, 

 heat now in the R. F. ; a bright azure-blue flame proves the presence 

 of copper. 

 Mix the roasted mineral with 4 parts soda, 1 part borax, and 

 some coal dust to a stiff paste with a little water. The charge is 

 reduced on coal, and is finally heated in the blue cone of the O.F. 

 until thoroughly fused, when it is cut away from the coal and 

 ground in the mortar under water. The copper buttons or scales, 

 being malleable, will not grind down, but the slag and coal will be 

 broken up and washed away, leaving the red scales of metallic 

 copper. 



Cadmium, Cd. Atomic weight, 112.4. Fusing point, 321.7 C. 

 a. Coat. Cadmium compounds when heated with soda and 

 borax in R. F. are reduced ; on continued heating, the metal is 

 volatilized, yielding an orange-yellow oxide of cadmium coat. Cad- 

 mium when associated with lead may be difficult to detect as a 

 coat ; in such cases the coat is scraped from the coal and treated 

 a closed tube with the O. F. ; care is taken not to heat the tube 

 ot enough to drive off lead or zinc ; a yellow ring of cadmium 

 xide will form just above the assay. If much is present, it will 

 form a metallic mirror. 



