What happened that caused Johnny to get terribly hurt? Who was the cause of his misfortune?

On Sunday, Johnny works on the basin as planned. Dove, Dusty, and Mrs. Lapham all help him in the shop. Entrusted with this important task, Johnny becomes even more insufferable than usual. He bosses everyone around and even speaks rudely to Mrs. Lapham. To get revenge, Dove hands him a cracked crucible to melt the silver in. He thinks the silver will spill on the furnace and make Johnny look like a fool. This happens exactly as Dove plans. When Johnny sees the spill, he is so surprised he slips and his right hand lands on the furnace.