Before the ice is in the pools
Serial negatives
Six "before" clauses delay the main statement. Dickinson piles up everything that *hasn't* happened yet to build anticipation—a grammatical countdown.
Touch the hems
Biblical allusion to the woman who touched Christ's garment hem for healing (Mark 5:25-34). What's sacred but just out of reach in summer becomes accessible in winter.
Bridge metaphor
"Just a bridge away" suggests the threshold between life and death, or present and eternal. Walking distance, but you need a bridge to cross over.
The frock question
She asks if her mourning dress will "answer"—will the dead respond? Or is she asking if grief itself will fit her again? The syntax makes both readings possible.