Martijn
Well-known member
As said: test with stannous for gold in solution if it is all precipitated.
if there is too much copper, or you've used too much SMB, You will have a dark stain, called a false positive. Dilute and try to see a purple color. It may be too dirty to properly see.
Test after dissolution with AR if you have gold in solution.
To get the suspended blacks to fall down, heat with a couple drops of sulfuric.
OR when dropping dirty AR solutions, dark green from copper: When in doubt, cement it out on copper and redissolve.
Martijn.
if there is too much copper, or you've used too much SMB, You will have a dark stain, called a false positive. Dilute and try to see a purple color. It may be too dirty to properly see.
Test after dissolution with AR if you have gold in solution.
To get the suspended blacks to fall down, heat with a couple drops of sulfuric.
OR when dropping dirty AR solutions, dark green from copper: When in doubt, cement it out on copper and redissolve.
Martijn.