2,620. How to Cover the Blood

Hilchos Shechita 14:13

We may cover blood using soot from an oven, antimony, the dust of mills, and ashes, whether ashes of trees, of garments, or even the ashes of burnt meat because Numbers 19:17 refers to “the ashes of the burnt sin offering.” It is permitted to cover blood using the ashes of a city that was led astray into idolatry (and burned as a consequence).

Hilchos Shechita 14:14

One who slaughters must put dirt below, then slaughter into it, after which he covers the blood with earth. One may not slaughter into a vessel and then cover it with earth.