As was ever true of any work that entailed the bending and beating of metal, the conversion of the tuns took longer than anticipated. What Jack was after was a single great round-bottomed wide-mouthed boiler, and a means to suspend it over a "bloody enormous" fire. This was simple enough. But at a later, critical stage of the operation he needed to clamp a sort of hat down over the maw of the kettle, and channel the vapors along a tube to another, smaller vessel where they could be bubbled through water. For the most practical of reasons, it was preferable that this latter vessel be made of glass. But it had proved difficult to get a glass container so large, and so they made do with copper. This explained what happened to Padraig; for against Jack’s express instructions, he had, while they were making a trial batch, lifted the lid to peer inside, and been greeted by a jet of white flame.