One Spoon or Two?

I needed to clean some mercury which I had been given by a classmate of mine in college many years ago. So I googled a bit and came across various methods, many with distillation involved, but then one caught my eye.

SUGAR!

It seemed so simple I gave it a go. In to your dirty metal put some sugar, shake it for 2 minutes and scrape off the dirty sugar.

Add some more and repeat.
And there it was, clean mercury. Now, I can't say how clean, but a huge difference to how it started out.


It had me thinking about the days when making gold was easy and so was going mad with heavy metal poisoning. The Alchemists must have added everything to mercury to see what happened. Perhaps sugar was one thing they tried.
Any ideas whats happening here chemically? Why should the dirt stick to the sugar?