When you said the water was "impure" in your previous comment, no one thought you meant it was sullied with... air. While not technically incorrect, if you honestly thought "impure" was a good way to describe water with air dissolved in it, the best I can say is to watch out for your subtext when using a word much differently than basically anyone else does.

I don’t think referring to dissolved gas in water as an impurity is all that uncommon. To quote wikipedia:

> Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. [1]

Other sources list carbon dioxide, oxygen, and nitrogen as impurities that can cause corrosion in pipes [2], or can form bubbles in systems where there are major changes in pressure or temperature, blocking pumps, fine tubing, filters, etc. [3]

So it’s a bit context dependent, but there are situations where it is totally reasonable to view dissolved gases in water as an impurity. And this context - the discussion of what makes ice clear or cloudy - is one of them.

How can you claim so confidently that “no one thought” something, or that the parent is “using a word much differently than basically anyone else”? If you honestly think that you speak for all 1.35 billion English speakers in the world - or even all the people reading this thread - the best I can say is speak for yourself.

[1] https://en.m.wikipedia.org/wiki/Water_purification

[2] https://www.watertechnologies.com/handbook/chapter-01-water-...

[3] https://www.elgalabwater.com/dissolved-gases

Yes, I used very slight hyperbole with "no one". Counterexample found, film at 11. A few highly technical contexts don't change the point: If someone holds up a flask of water and says "this is impure", what's at the top of the list of possible impurities in your mind, and how far down the list is air?

If by purity you mean any sort of "alien substance" whatsoever, stick with liquid water. And I hope you don't like any colored minerals, as those all have "alien substances" inside.