Mishnah for Shekalim 8:1

Derivatives of water are: the liquids that come from the eye, from the ear, from the nose and from the mouth, and urine, whether of adults or of children, whether [its flow is] conscious or unconscious. Derivatives of blood are: blood from the slaughtering of cattle and wild animals and birds that are clean, and blood from bloodletting for drinking. Whey is like milk, And the sap of olives is deemed like oil, since it is never free from oil, the words of Rabbi Shimon. Rabbi Meir says: even though it contains no oil. The blood of a sheretz is like its flesh, it causes uncleanness but does not cause susceptibility to uncleanness, and there is nothing else like it.

Rabbi Joshua ben. Bathyra testified concerning the blood of carcasses that it was pure. Rabbi Shimon ben Bathyra testified concerning the ashes of purification, that if a defiled person had touched part of them he had defiled the whole of them. Rabbi Akiva added in regard to the fine flour, the incense, the frankincense, and the coals, that if a tevul yom had touched part of them he had made the whole of them unfit.