On the outskirts of Dallas, Texas, at an unassuming warehouse, two young men in scrubs carefully weigh out liquid nicotine. All they do is measure, actually. They move back and forth in a clean room, a carefully engineered space intended to keep out unwanted airborne particles. It almost sounds windy when you open the door.
A computer spits out what they need—this much propylene glycol, this much vegetable glycerin, this much flavoring—before the e-liquid barrel moves onto a gyroscopic mixer. [...]