[Regarding] shards of earthenware that were used for tamei beverages, and they fell into the airspace of an oven, [if] the oven was heated, it is tamei, because the beverage will eventually emerge. And similarly with new marc, but in [the case of] old [marc, the oven is] tahor. And if it is known that beverage comes out of it, even after three years, [the oven] becomes tamei.