| 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 |