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The second last sentence implies that arsenic smells like bitter almond, too. Is that correct, a mistake or just used synonymous to "poison"? According to dict.cc, it isn't.
Neither. That sentence implies that writers frequently mix up arsenic and cyanide, attributing aspects of cyanide to arsenic.
This example didn't reference a work. Moving it here in case someone can identify the source.
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How well does it match the trope?