This article presents the history of the "Duke-Fingard" domestic medical vaporizer. It considers the emergence of this Canadian device out of Rudolph Duke and David Fingard's larger institutional inhalation treatment system, and seeks to trace and explain the medical, social, commercial and cultural influences that shaped its subsequent sale, use of electricity, and design. What emerges through this synchronic and microhistorical analysis is a more concrete sense of the practice of domestic medicine during a transformative period of Canadian medical history.