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Comment by maxwellg | Hacker News Reader

What does the additional .09% of purity get you - if the xenon or nitrous is mixed with air at inhalation time anyway? For example, divers and pilots use ABO oxygen which is only 99.5% pure.

https://www.aopa.org/news-and-media/all-news/2023/december/p...

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It's often what the 0.9% is that makes the difference between grades, other than purity.

Generally and as an illustration, a chemical may have a 99% "reagent" grade that includes industrial solvents or some other chemicals that are toxic to ingest. So its equivalent "food" grade may have the same 99% purity but the other 1% is something that isn't poisonous.

My chemistry teacher pointed out to our class that "99%" ethanol was distilled in benzene, and therefore had poisonous residue, whereas "95%" was water distilled, and thus safe to spike your OJ.

In the US they generally add toxic chemicals back in for that kind of thing to prevent people doing that.

They might generally add toxins (or bitterants) to the 95% if regulations instruct them to.

With the 99% stuff, the laws of physics compells them to use the benzene.

Financial considerations also exert an influence on the process.

Such toxins are added to make the alcohol unsuitable for human consumption, and thus avoid paying government alcohol tax or duty.

Where I am it's called "methylated spirits" and IIRC the boing point of the additive is very close to that of the alcohol so it's not possible to distill it out.

20 years ago I read about a Dutch company that sold pure alcohol for consumption to Russia, where people would drink one sip of pure alcohol followed by two sips of orange juice.

Hopefully the only country with a market for that.

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