In just a few lines, the speaker describes an evening spent eating with a woman and the surprising warmth it leaves behind. The title, "Love's alchemy," sets up the central comparison: the speaker is like an alchemist, someone who tries to turn ordinary material into something precious. What the speaker "found" at dinner is the heat an alchemist would carry home in a bottle, a kind of captured, concentrated feeling.
The last two lines make that feeling more specific. It is "a letter from July," which suggests something warm, personal, and out of season, perhaps a memory or a message that arrives with summer inside it. Then come "wind and fever," two things that don't sit comfortably together. Wind is restless and fleeting, while fever is intense and a little dangerous.
The mood is hushed, intimate, and slightly dizzy. The speaker seems happy but also unsettled, as if falling for someone feels like both a gift and an illness.