Which refractometer?

[SpyC]

Mercury? Not in mine.. Those bits at the bottom are made of lead (at worst) but also possibly simple iron beads.
I turn off all pumps - put the hydrometer in the tank for 10 seconds, observe where the readings are and job done!

I had read elsewhere mercury was in it. The beads are just weights and not where I would expect mercury to be. Maybe the posts I saw regarding mercury had this confused with older thermoeters.

 

[Borat]

I had read elsewhere mercury was in it. The beads are just weights and not where I would expect mercury to be. Maybe the posts I saw regarding mercury had this confused with older thermoeters.

Mercury would serve no purpose here - perhaps as you said you got confused about some other thermometer conversation.

Cheers,

Borat.