[bigblock (OP)]

Just wondering if I will ruin my PTFE coated stir bar if used in hot Aqua Regia

[damocles]

It should be just fine (but I will not take responsibility if it is not [])

[damocles]

A pyrex encased magnet might be cheaper and less of a worry. (Put a small rod magnet in a glass tube where it is a fairly snug fit, and either seal both ends with a cutting flame or get your local friendly glassblower to do it).

[lightarrow]

A pyrex encased magnet might be cheaper and less of a worry. (Put a small rod magnet in a glass tube where it is a fairly snug fit, and either seal both ends with a cutting flame or get your local friendly glassblower to do it).

This is interesting, but I imagine the metal/magnet bar shouldn't be tightly fitted or the different thermal expansion coefficient could break the glass when heated.

[damocles]

Yes lightarrow, that would certainly be a good idea. Magnet materials certainly expand more than pyrex, though neither expands much. I did not really mean 'tight' by 'snug', but perhaps it would be wise to be a little more conservative and specify 'an audible rattle' for the room temperature fit. When I was at Uni as a student in the 1960s teflon was a very expensive material, and most of the stirring rods in our teaching labs were home made glass ones of this sort.

Is bigblock wanting to dissolve platinum or something? (Gold goes quite happily in cold aqua regia; platinum is painfully slow, even in hot).

[bigblock (OP)]

Thanks for the information. I used it today in boiling aqua regia and it held up just fine. Yes Damocles, I am attempting to leach platinum grains. It looks like this will be very slow just as you said.

[lightarrow]

Don't know but maybe Pt could be dissolved in melted NH₄HSO₄. I have no Pt to try with  []