Yosef Karo

“ Soak the lung in water a 24 hours period. In cold weather soak it in temperate water and in a vessel the water does not ooze out of and leak so it doesn't get cold quickly. And in hot weather soak it in cool water in a vessel the water doesn't ooze out of so it can stay cool. If it returns to a healthy state behold it's due to an act of Heaven or other creatures and it's permitted. If it does not return to a healthy state it's due to man and it's treif. ”

“ And it's only called atum if its appearance is alike with the rest of the lung except it doesn't rise when inflated. But if its appearance is like pus (mugla) it's just a large, hard tubercle (tinri) and it's kosher without checking. ”

“ Because the other one is firm and does not shield it. But if it's perforated facing the lung flesh, the flesh shields it and it's kosher.
7 A lung whose contents can be poured like a pitcher [i.e., whose tissue dissolved to the point of liquefaction, Sukkah 36a] but its outer membrane is intact with no holes - if the bronchia stay in place and are not dissolved, it's kosher. But if even one bronchus is rotted it's treif. How do we determine? We pierce [the lung] and pour it into a container that's lead glazed [Taz: the Tur explains that it's white] . ”