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It's the bit after 42 minutes in and the bit about methylene blue and the magnet test, tho i don't suggest buy from them, or even buy for that matter. but sure interesting.
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From @chrisyt1
Posting for
It's the bit after 42 minutes in and the bit about methylene blue and the magnet test, tho i don't suggest buy from them, or even buy for that matter. but sure interesting.