Dust, Remedies, and the Reverend's Complaint

Your apothecary — Holt & Daughter, est. 1887 — sits on the sun-baked main street of Sable Creek, dispensing remedies, gossip, and the occasional miracle since before the railroad came. Today Reverend Pryce has arrived red-faced and insistent: his prize rosebush has a blight, and he wants your strongest copper-sulphate spray. Problem is, you've just mixed the last of it wrong — too weak — and your copper-sulphate tin is empty. But there is something behind the counter that could fix this, if you use it in a way it was never meant to be used.