358 PROCEEDINGS OF SECTION B. 



These scales were not the easiset things to decompose : aqua reqia 

 had very little effect on them ; but they were decomposed by hot 

 concentrated sulphuric acid. 



A similar compound to this is described by Hampe as " copper 

 mica," which consists of an antimoniate of copper and nickel, having 

 the formula of 6 CujO, SbjOs + 8 NiO, SbjOs, except that in the analysis 

 given the antimony has been largely replaced by arsenic, and a fair 

 amount of lead is also present. 



In other instances nickel has been present in the slimes with which 

 I have had to deal, but never over -J per cent, going, as this impurity 

 should, into the electrolyte. 



Selenium. — This element remains to a certain extent with the 

 copper, and is found in that metal after the refining process is finished. 

 In the electrolytic refining the selenium goes down with the anode slime, 

 and on boiling this with sulphuric acid and air to extract the copper 

 the selenium is still found with the remaining slime. 



Some time ago I had a slime containing a fair amount of selenium, 

 but its presence was unknown to me. However, on treating the boiled 

 slime on a cupel with lead, a product was obtained which caused a 

 large amount of trouble. This product I at first took to be a copper- 

 lead regulus, but its behaviour in the furnace did not agree with what 

 one would expect from such a product. The litharge which was formed 

 seemed to have no action on it, but remained floating on top. 



A piece was then sent to the assay office, with instructions to have 

 it run down with twice its weight of litharge in a crucible ; but the 

 product was returned to me "with the litharge on top more or less con- 

 verted into silicate, and the regulus below apparently unchanged, 

 except that a little " moss copper " was showing at the bottom of the 

 button. Seeing the trouble this was causing by retarding the cupelling 

 operation, I had an analysis made, and finally found the material to 

 consist of selenium combined with copper and lead, and not with 

 sulphur, which I had at first thought to be the case. 



The following is an analysis of this substance : — p^^. ^^^^. 



Copper 39-330 



Lead 27-200 



Selenium 20-808 



Telurium 1-224 



Sulphiu- 4-440 



Silver 4-480 



Gold 0-012 



Total 97-494 



The other constituents being only small in amount, were not 

 determined. Once knowing the cause of the trouble, it was not a very 

 difficult matter to overcome it; the addition of a little nitrate of soda 

 to the cupel being all that was necessary. 



Although at times the sister element, telurium, has been present in 

 fairly large quantities in slime under treatment, it has never caused 

 any trouble except the difficulty of eliminating it from the gold and 

 silver bullion in cupelling. 



