Ohalos 2:6-7

Ohalos 2:6

Regarding the spine or skull from two corpses, a reviis of blood from two corpses, a quarter-kav of bone from two corpses, a corpse’s limb from two corpses, and a severed limb from two living persons, Rabbi Akiva says that these things convey ritual impurity but the Sages declare them ritually clean.

Ohalos 2:7

If a barleycorn-sized bone is split in two, Rabbi Akiva says it conveys impurity and Rabbi Yochanan ben Nuri says it doesn’t. Rabbi Yochanan ben Nuri points out that the Sages didn’t say “bones the size of a barleycorn,” they said “a bone the size of a barleycorn.” Regarding a quarter-kav of bones that was pulverized so that no piece is the size of a barleycorn, Rabbi Shimon declares it ritually clean while the Sages declare it unclean. If the limb of a living person is divided in two, it is  ritually clean. Rabbi Yosi declares it unclean but he agrees that if it was severed from the person in stages, then it is ritually clean.