Prior to the invention of the rubber eraser, tablets of rubber/wax were used to erase lead/charcoal marks from paper. Bits of rough stone such as sandstone or pumice were used by various cultures to remove small errors from parchment or papyrus documents written in ink. On April 15, 1770, Joseph Priestley described a vegetable gum which had the ability to rub out pencil marks: "I have seen a substance excellently adapted to the purpose of wiping from paper the mark of black lead pencil." He dubbed the substance "rubber".