Commento su Hullin 6:5

נתערב ביין – which is red and the appearance of the blood is not recognized in it.

Introduction Our mishnah deals with blood that comes out of a slaughtered bird or wild animal that then becomes mixed up with something else, either water, wine or blood.

רואין אותו – [we view that] wine as if [it is] water, for if the appearance of blood was recognized in the water according to this measurement, he would be liable to cover [the blood].

If the blood became mixed with water and it still has the color of blood, it must be covered up. If the blood becomes so mixed up with water, that it no longer has reddish color, then it is no longer considered to be blood and it need not be covered up. But if it still has the color of blood, it must be covered, despite the fact that there is water mixed in.

נתערב בדם בהמה – which is not something covered, and the majority of it is the blood of a cattle.

If it became mixed with wine, [the wine] is to be regarded as though it was water. Wine has the same color, more or less, as blood, so we can’t say that if the mixture has the color of blood then it must be covered up. Therefore, if there is enough wine such that if it was water there would no longer be the color of blood, then he need not cover it up. This is what it means when the mishnah states that the wine is regarded as water.

או בדם חיה – the blood bled by an animal–beast of chase or deer.

If it became mixed with the blood of a beast or with the blood of a wild animal, it is to be regarded as though it was water. Rabbi Judah says: blood does not annul other blood. The blood of a domesticated beast (cow, sheep or goat) need not be covered. If the blood of a wild animal or bird is mixed up with the blood of a beast, then we apply the same test as we did with blood that was mixed with wine. If there is enough wild animal or bird blood such that if the beast’s blood was water the mixture would still look like blood, then he must cover it up. This section has some very puzzling words “or with the blood of a wild animal.” The blood of a wild animal must be covered and therefore this line makes no sense in this context. Albeck suggests that it is here by mistake, due to the similarity between this mishnah and Zevahim 8:6 where the words “the blood of a wild animal” do make sense. Rashi suggests that the blood of the wild animal came out not by slaughtering, while the Rambam suggests that the wild animal referred to here is not a kosher one. Neither suggestion is convincing. Rabbi Judah says that blood can never annul the presence of other blood. While an overwhelming amount of wine or water could exempt a small amount of blood from having to be covered, the same cannot be said about blood. In general, Rabbi Judah holds that when two like things are mixed, the problematic thing (for instance nevelah meat mixed in with kosher meat) can never be annulled.

רואין אותו – that it is not required to cover [the blood], as if it were water, but if this blood is from the ritual slaughter of an animal–beast of chase and fowl and it is recognized, one is required to cover it.

אין דם מבטל דם – and even if the appearance of blood is not recognized in the water like the blood of this cattle, the blood of animals–beasts of chase are not nullified, for he holds that a mixture of homogeneous things (of which one is forbidden), the rule of neutralization by quantity takes no effect (see Talmud Hullin 100a). But the Halakha is not according to Rabbi Yehuda.