Sodium metabisulfite

[Yggdrasil]

Now I have more pictures to post, which may help to identify what was the initial problem.

View attachment 52271
This is after first digestion in AR. Then it was denoxed, cooled to about 28C with ice and filtered. After that I attempted to drop gold with saturated solution of SMB, which failed. Stannous test showed dark brownish spot after failed drop. I underestimated the amount of gold by at least 50%, but there was good margin of dissolved SMB.

View attachment 52272
This is after cementing with copper, and redissolving with AR. There is some material floating on the top of pregnant solution which I didn't expect. Then it was again denoxed, cooled with ice, filtered and dropped with copperas. This time it worked.

How is this solution made?
Is it the same as the first post?