杏吧原创

I live in a hard-water area and find that vinegar is a cheap and effective way to descale my kettle. But no matter how much I rinse afterwards, I won't get a decent cuppa for a week. Given that the kettle is stainless steel and plastic, why does the taint stay so long? A proprietary citric acid descaler presents no such problem, but is less effective and more expensive.

Earth

Health

I do cryptic crosswords. On my first attempt, I usually finish about half the clues and get stuck. When I return to the crossword the following day, even if I haven't been consciously thinking about it, I usually get a few more clues very quickly. But after half an hour at most, I become stuck again. What's going on?

Earth