Ohalos 13:5-6

Ohalos 13:5

The following things reduce the opening of a handbreadth: less than an olive-sized piece of flesh reduces a quarter of a kav of bones; a smaller than barleycorn-sized piece of bone reduces with an olive-sized piece of flesh; a smaller than olive-sized piece of a corpse; a smaller than olive-sized piece of carrion; a smaller than lentil-sized piece of vermin (sheretz); a smaller than egg-sized portion of food; produce from the window (growing distanced from the wall); a spider web that has substance; the carcass of a kosher bird that one didn’t decide to eat; the carcass of a non-kosher bird that one intended to eat but that had not been rendered susceptible to ritual impurity or that had been rendered susceptible to ritual impurity but was not intended to be eaten.

Ohalos 13:6

The following things don’t reduce the opening of a handbreadth: bone doesn’t reduce for bones; flesh doesn’t reduce for flesh; an olive-sized piece of a corpse doesn’t reduce; not an olive-sized piece of carrion; not a lentil-sized piece of vermin; not an egg-sized portion of food; not produce from the window (growing near the wall); not a spider web that lacks substance; not the carcass of a kosher bird that one intended to eat; not the carcass of a non-kosher bird that one intended to eat and that had been rendered susceptible to ritual impurity; not warp and woof threads that are infected with negaim (a form of impurity); not a brick from a beis haperas (a plowed field that contains a grave); this reflects the opinion of Rabbi Meir. The Sages say that the brick does reduce the handbreadth because the soil of a beis haperas is ritually clean. The general principle is that ritually clean things reduce the handbreadth while ritually unclean things don’t.