My grade 12 shop teacher in California walked us through everything on the first day of class. He had a mixed shop, for metal, wood, stained glass, whatever we wanted to work with really. When he got us all in a circle around the blast furnace, where some 'pot metal' was heating up for a pour, he smiled a broad smile then said "everyone look up." We did, and there on the ceiling acoustical tile, 20 or 25 feet up, was a large clear area in the shape of a head and shoulders... surrounded by shiny spots of metal. As we looked down again he had a serious expression and explained "the kid lost one eye, some sight in the other eye, his face didn't look great... anyone want to guess how this happened?" Nobody could guess, so Mr Malvestiti (I think that's how it was spelled) explained "He wondered what would happen if he spat into the molten metal. He found out." Basically a steam-powered cannon I guess. Must have been a lot of saliva. We all looked at that ceiling often. Hell of a lesson right there.