Note C — TREATISE ON HAT-MAKING AND FELTING.
Reading edition
Hatters' kettles for FUR hatting are made of copper, as they take less firing than those that are made of lead. But lead must be the metal if sulphuric acid, no matter in how small quantity, is used in the water. It is generally resorted to by the men in sizing WOOL hats, as it facilitates the felting operation. This acid (vitriol), having no affinity for lead, does not affect the kettle, while it would soon eat the one of copper through. Care, however, must be taken that no stone be let fall into the water of the lead kettle, for a hole will soon result from such an accident.