או בדם החיה רואין אותו כאילו הן מים רבי יהודה אומר אין דם מבטל דם
or with blood of the undomesticated animal that did not flow from the neck and does not require covering, one views the blood as though it is water. Rabbi Yehuda says: Blood does not nullify blood. Therefore, even if the undomesticated animal’s blood, which one must cover, is not recognizable in this mixture, he is obligated to cover the mixture nevertheless.
דם הניתז ושעל הסכין חייב לכסות אמר רבי יהודה אימתי בזמן שאין שם דם אלא הוא אבל יש שם דם שלא הוא פטור מלכסות:
With regard to blood that spurts outside the pit over which the animal was slaughtered, or onto a wall, and blood that remained on the slaughtering knife, one is obligated to cover it. Rabbi Yehuda said: When is this the halakha? When no blood remains there from the slaughter except that blood. But if blood remains there from the slaughter that is not that blood, he is exempt from covering it.
גמ׳ תנן התם דם שנתערב במים אם יש בו מראית דם כשר נתערב ביין רואין אותו כאילו הוא מים נתערב בדם בהמה או בדם החיה רואין אותו כאילו הוא מים רבי יהודה אומר אין דם מבטל דם
GEMARA: We learned in a mishna there (Zevaḥim 77b): In the case of blood of an offering fit for sacrifice that was mixed with water, if the mixture has the appearance of blood it is fit for sprinkling on the altar, even though the majority of the mixture is water. If the blood was mixed with red wine, one views the wine as though it is water. If that amount of water would leave the mixture with the appearance of blood it is fit for presentation. And likewise, if the blood was mixed with the blood of a non-sacred domesticated animal or the blood of a non-sacred undomesticated animal, one considers the non-sacred blood as though it is water. Rabbi Yehuda says: Blood does not nullify blood. Therefore, the priest presents the blood of the mixture on the altar.
א"ר חייא בר אבא אמר ר' יוחנן לא שנו אלא שנפלו מים לתוך דם אבל נפל דם לתוך מים ראשון ראשון בטל
The mishna teaches that in a case where water became mixed with the blood of an offering, if the mixture has the appearance of blood it is fit, despite the fact that there is more water than blood. Concerning this Rabbi Ḥiyya bar Abba says that Rabbi Yoḥanan says: They taught this halakha only in a case where the water fell into the blood. But in a case where the blood fell into the water, the first drop of blood, and then the next first drop of blood, are nullified in the water, i.e., each drop is nullified in turn. Consequently, the mixture is unfit for presentation, regardless of whether it has the appearance of blood.
אמר רב פפא ולענין כסוי אינו כן אין דחוי אצל מצות
Rav Pappa says: But with regard to the mitzva of covering the blood of birds or undomesticated animals that are slaughtered, it is not so. In this case, even if the blood fell into water the mitzva of covering applies to it, provided the mixture has the appearance of blood. The blood is not nullified by the water because there is no permanent rejection with regard to mitzvot other than those that relate to sacrificial rites. Therefore, its nullification was merely temporary, but once there is enough blood in the water it reassumes its status of blood.
אמר רב יהודה אמר שמואל כל מראה אדמומית מכפרין ומכשירין וחייבין בכסוי מאי קמשמע לן מכפרין תנינא חייבין בכסוי תנינא
§ With regard to mixtures of blood and water, Rav Yehuda says that Shmuel says: All mixtures of blood and water that maintain a reddish hue are considered blood and effect atonement by being presented on the altar, and render food susceptible to contracting ritual impurity, and are included in the obligation of covering the blood provided that the blood is from the slaughter of an undomesticated animal or bird. The Gemara asks: What is Rav Yehuda teaching us? If he is teaching us that such mixtures effect atonement, we already learn this from the mishna in tractate Zevaḥim. And if he is teaching us that such mixtures are included in the obligation of covering the blood, we already learn this in the mishna here.
כשירין איצטריכא ליה מכשירין נמי אי דם אכשורי מכשר אי מיא אכשורי מכשרי לא צריכא שתמדו במי גשמים
Rather, it was necessary for Rav Yehuda to teach that such mixtures render food susceptible to contracting ritual impurity, as this was not taught in a mishna. The Gemara challenges: It is also unnecessary to teach that such mixtures render food susceptible to contracting ritual impurity. If the mixture has the status of blood it renders food susceptible, as does blood, and if the mixture has the status of water it renders food susceptible, as does water. The Gemara responds: No, this statement is necessary in a case where the blood was mixed with rainwater, which does not render food susceptible without the intent or desire of the owner of the food. If the mixture is considered blood it renders food susceptible.
מי גשמים נמי כיון דשקיל ורמי אחשבינהו לא צריכא שנתמדו מאליהן
The Gemara challenges: With regard to rainwater as well, since one took it and placed it into a vessel containing blood, he has ascribed significance to the rainwater and it should be capable of rendering food susceptible. The Gemara responds: No, this statement is necessary in a case where the rainwater was mixed with the blood by itself, i.e., it was not gathered and poured purposefully.
ר' אסי מנהרביל אומר בצללתא דדמא רבי ירמיה מדפתי אמר ענוש כרת והוא דאיכא כזית במתניתא תנא מטמאים באהל והוא דאיכא רביעית
Rabbi Asi of Neharbil says: The statement of Rav Yehuda is referring to blood plasma, i.e., if the plasma has a reddish hue due to the blood, it has the status of blood and can render food susceptible to contracting ritual impurity. Rabbi Yirmeya of Difti said: Consumption of this plasma is punishable by karet, as is the halakha with regard to one who consumes blood (see Leviticus 17:14), provided that there is at least one olive-bulk of actual blood. It was taught in a baraita: Blood plasma that issues from a corpse that has a reddish hue imparts ritual impurity in a tent, provided that there is at least a quarter-log of actual blood, which is the amount of a corpse’s blood that imparts ritual impurity.
תנן התם כל משקה המת טהורין חוץ מדמו וכל מראה אדמומית שבו מטמאין באהל ומשקה המת טהורין ורמינהו משקה טבול יום (משקין היוצאין ממנו) כמשקין שנוגע בהן
We learned in a baraita elsewhere (Tosefta, Oholot 4:5): All liquids that issue from a corpse, e.g., teardrops or breastmilk, are ritually pure, except for its blood. And all liquids that issue from a corpse that contain a reddish hue of blood impart ritual impurity in a tent. The Gemara asks: But are liquids that issue from a corpse ritually pure? And raise a contradiction from a mishna (Tevul Yom 2:1): With regard to liquids that issue from one who immersed that day, liquids that issue from him have the same status as liquids that he touches.