These must be removed on Pesach: Babylonian kutach, Median beer, Idumean vinegar, Egyptian zisom, dyers' broth, cooks' dough and scribes' paste. R' Eliezer says: also women's cosmetics.  This is the general rule: Whatever is of a species of grain must be removed on Pesach. These are in the category of a prohibition but they are not subject to kares.

When dough remains in the grooves of a kneading trough, if there is as much as an olive's [volume] in one place, he must remove [it]; but if not, it is null because of its insignificance. And likewise regarding the [laws of] contamination. If he objects to it, it interposes; but if he desires it to remain, then it is as the trough.  [Regarding] “deaf” dough, if there is [dough] similar to it that has already leavened, it is forbidden.

How do we separate challah from contaminated dough on the festival?  R' Eliezer says: She should not designate it with the name [challah] until it is baked. R' Yehudah ben Beseira says: Let it be cast into cold water.  Said R' Yehoshua: This is not the leaven concerning which we are warned, It shall not be seen (Exodus 13:7) and It shall not be found (Exodus 12:19). But he separates it and leaves it until the evening; and if it leavens, it leavens.

Rabban Gamliel says: Three women may knead at the same time and bake in the same oven, one after the other. But the Sages say: Three women may be occupied with dough [simultaneously]: one kneads, another shapes, and a third bakes.  R' Akiva says: Not all women and not all kinds of wood and not all ovens are alike.  This is the general rule: If [the dough] rises let her wet it with cold water.

Partly leavened dough must be burned, but one who eats it is exempt [from punishment]. Furrowed dough must be burned and one who eats it is liable to kares.  Which [dough] is [classified as] “partly leavened”? — [When the furrows are] like locusts' horns. [Which is classified as] “furrowed”? — When the furrows run into each other —- [these are] the words of R' Yehudah.  But the Sages say: [If] one eats either of these he is liable to kares. [If so,] which is “partly leavened dough”? — Whenever its surface turns pallid, like [that of] a man whose hairs stand on end.

[If] the fourteenth [of Nissan] falls on the Sabbath, we remove everything before the Sabbath —- [these are] the words of R' Meir.  But the Sages say: [Everything is removed] at its [usual] time;  R' Elazer bar Tzadok says: Terumah [must be removed] before the Sabbath and chullin at its [usual] time.

[If] someone is going to slaughter his pesach-offering, to circumcise his son, or to dine at a betrothal feast at the house of his father-in-law, and he remembers that he has chametz at home —- if he is able to return, remove [it], and [then] return to his mitzvah, he must go back and remove [it]; but if not, he nullifies it in his heart.  [If he is on his way] to save [people] from a [marauding] troop, from a river, from bandits, from a fire, or from a collapsed building, he nullifies it in his heart. [If] it was but to establish a voluntary resting place, he must return at once.

Similarly, [if] someone left Jerusalem and remembered that he had sacrificial meat in his hand —- if he has passed Tzofim, he burns it where he is; but if not, he [must] return and burn it before the Temple with the wood of the [altar] pyre.  And for how much [chametz or meat] must they return? — R' Meir says: In either case, [when there is] as much as an egg; R' Yehudah says: In either case, [when there is] as much as an olive. but the Sages say: [For] sacrificial meat, as much as an olive, but [for] chametz, as much as an egg.