I accidentally fell down a deep rabbit hole while trying to figure out how pH meters work. I thought this would be a really nice simple example of a scientific instrument, suitable for didactic explanation as part of an exposition of the failures of logical positivism. FAIL
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It appears to be literally true that no one knows how the better type works. They use a “glass electrode” that is semipermeable to hydrogen ions. The nature of the electrode is a closely-guarded trade secret and they appear to be discovered by trial and error, not theory.
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pH meters are peevish as hell and give maliciously wrong readings unless you are extremely polite to them. You have to recalibrate them before every measurement in case they are in a bad mood.
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I tapped out while trying to understand a long, vitriolic, hyper-technical argument about whether pH meters actually measure H+ (per the undergrad definition) or H3O+ (which is what you get in aqueous solution) and whether it matters.
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Here’s an interesting thread from someone who actually knows what they are talking about (I assume):https://twitter.com/evanbd/status/1141540083532795904 …
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End of conversation
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I hate everything.
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