356 PROCEEDINGS OF SECTION B. 



reverb erat or y. I have had most to do with this metal in the electrolytic 

 refining of copper containing it, the highest amount present in 

 the anode copper being just over |- per cent., which is more than 

 enough to render any copper unsuitable for commercial purposes. 

 The behaviour of this impurity in electrolytic copper refining is peculiar. 

 It is always found, from my experience, like antimony, to a more or 

 less extent, in the cathode copper, though the amount, if properly 

 refined, is very low, running in the fom'th place of decimals. 



I have noticed that with some copper containing only -04 per cent, 

 of bismuth that in refining as much as half of this has been plated out 

 with the refined copper ; and, on the other hand, I have refined copper 

 containing from -2 per cent, to -3 per cent., and yet the bismuth in the 

 finished product has only been found in the fourth place of decimals. 

 This, I have come to the conclusion, is largely due to the state in which 

 the bismuth exists in the original anode copper refined, but unfortunately 

 I had no opportunity of verifying my opinion on this matter. 



In the first case, where such a large percentage of the bismuth 

 plated out from the smaller amount present in the anode copper, the 

 pitch of the metal was that of refined copper assaying 99-6 per cent, 

 of copper ; in the second case the pitch of the copper was under blister 

 containing from 97 per cent, to 98 per cent, of copper, so that I believe 

 much depends on the form in which the bismuth is present in the anode 

 metal. 



In the first case the bismuth was probably present in the anode 

 as either an oxide or metal, and in the second case present as sulphide, 

 so that it was in an easier form to dissolve in the first case than in the 

 second, and once having passed into solution a certain amount plated 

 out. This, I think, must have been the cause of the difference in the 

 behaviour of the impurity. 



It may have been that in the second case the bismuth was in com- 

 bination with some other impurity, as the anode metal was very foul 

 with antimony and lead, but I am inclined to think it was more probably 

 due to the first explanation. Unfortunately, I could not get the oppor- 

 tunity of having the pitch of the anode copper altered in the first case, 

 so was unable to ascertain whether my theory was right or otherwise. - 



During the refining of the " blister pitch " anodes containing tha 

 high percentage of bismuth, a very peculiar product was obtained in 

 the form of a gelatinous white slime, which coated with cathodes 

 thickly on the outside, but did not deposit in the copper itself. This 

 could easily be scrubbed off, leaving the copper clean and only con- 

 taining traces of impurities. 



The following is a partial analysis of this material : — 



The undetermined consisted principally of carbon, hydrogen, 

 oxygen, some sulphur, and silver and gold. This material apparently 



