2,550. An Important Principle

Hilchos Shechita 7:8

An important kashrus principle to remember is that if air is blown into a lung that’s submerged in lukewarm water and the water doesn’t bubble, the lung is whole and unpunctured.

Hilchos Shechita 7:9

Let’s say that a lung can be poured as if from a pitcher but its outer membrane is whole and unpunctured. If the bronchioles are still in their place and haven’t deteriorated, the animal is kosher; if even one of the bronchioles has deteriorated, the animal’s a treifa. In such a case, we puncture the membrane and pour it into a vessel glazed with lead or something similar. If white threads are seen, we know that the bronchioles have deteriorated and the animal’s a treifa. If such is not the case, then only the flesh of the lung has deteriorated and the animal remains kosher.