Ohalos 8:5-6

Ohalos 8:5

The following things neither convey nor block ritual impurity: seeds and vegetables that are still attached to the ground except for the exceptions already mentioned (in 8:1); hailstones, snow, frost, ice and salt; anything that hops or jumps from place to place; a flying bird, a flapping cloak, and a boat floating on the water. If the boat is tied with something that can hold it in place, or if a stone is placed on the cloak, then these things can convey impurity. Rabbi Yosi says that a house on a boat doesn’t convey impurity.

Ohalos 8:6

Let’s say that there are two earthenware jars with tight-fitting lids, each of which contains half of an olive-sized piece of a corpse. If these are placed in a house, they remain clean but the house is rendered unclean. If one of the jars is opened, that jar and the house are rendered unclean but the other jar remains clean. The same is true of two rooms that open into a house.