An olive-worth of meat that falls into a pot of boiling milk: let a non-Jew taste the dish. If he says that there is a taste of meat in it, it is forbidden. If not, it [the milk] is permitted, even in less than sixty, and that piece [the meat] is forbidden. When is this true? When one quickly removes the piece before it exudes the milk that it absorbed, meaning before the pot rests from its boiling. But if he didn't remove it before it was able to exude the milk it absorbed, even if a non Jew tastes it and it has no taste at all, (Rama) it's forbidden unless there is sixty. See chapter 98 (Shulchan Arukh, Yoreh De'ah 98) that we aren't accustomed to rely on the tasting of a non-Jew and we need sixty every time.
Milk falls into a pot of meat: [let a non-Jew] taste the piece that the milk fell on. If it does not taste of milk, everything is permitted. If the piece does taste of milk, then that piece is forbidden. For us who don't rely on a non-Jew, we need sixty in the piece, and if there's not sixty then it's all forbidden. And we measure it [the original piece of meat] against the whole [pot]. If there was in all that is in the pot, the pieces, the vegetables, the soup, and the spices, enough that this piece is one in sixty [or less] of the whole, the piece is forbidden and the rest is permitted. In what situation are we speaking? When the pot was not stirred at the beginning when the milk fell in, but only at the end, and the pot wasn't covered. But if it was stirred from beginning until end or was covered from the time of [milk] falling in until the end, everything joins together to nullify the taste of milk. Therefore, if it wasn't stirred at all, not at the beginning and not at the end, and wasn't covered at all, if there is sixty in the pot compared to the drop of milk that fell in, it only prohibits the piece alone, and the rest of the pot is permitted (Bet Yosef in the name of the Ra'avid and Magid Mishnah in the name of the Rambam.) And also if it was stirred at the beginning or covered immediately even though it wasn't stirred or covered at the end, all of the pot joins together, if it was stirred or covered immediately when the prohibited matter fell in (Tur and Bet Yosef in the name of the Ri N Haviv.) Therefore, if [the milk] fell into the soup or onto a piece and we don't know onto which piece it fell, stir the whole pot until it's all mixed. If in the whole pot there is a taste of milk, it's prohibited, and if not, it's permitted. And if there is no non-Jew to taste and be relied on, we measure with sixty (until now, the language of the Rambam.) There are those who disagree and reason that stirring the pot isn't effective unless it's stirred immediately after the prohibited matter fell in, and this is our practice.
When a piece of meat becomes forbidden due to milk it is prohibited completely. If it was cooked with others, sixty is needed to negate it all. If you recognize it, take it out and the others are acceptable. If you don't recognize it, the sauce is permitted but all the pieces of meat are forbidden if the initial piece was roeeya latchabel (too important to be considered part of a mixture)
We only say the rule of "the piece itself becomes just as forbidden as a neveila" by milk and meat, but not by other prohibitions, like an olive's bulk of forbidden fat that was absorbed by a piece of meat, and there isn't sixty times [the meat] to nullify [the fat], and it becomes forbidden, and afterwards it was cooked with other meat we only require [the new total] to have sixty times the olive bulk of the fat, and if so, then even the [original] piece of meat itself returns to become permitted. Rema: And there are those that say that we apply to all prohibitions the rule of "the piece becomes just as forbidden as a neveila", and this is the regular custom and it should not be changed. And this is precisely if the forbidden item is attached to the permitted piece of meat, or if the piece of meat is entirely outside of the sauce and the forbidden item fell onto it. But, if part of the piece of meat is inside the sauce and the prohibitted item is not attached to it, we do not say "the piece of meat becomes just as forbidden as a neveila" and the entire pot would combine [to sixty times the forbidden] to nullify the forbidden item. Nevertheless, there is what to be stringent about and to forbid that piece of meat. And all of this is regarding other prohibitions, but by milk and meat, even though there is no forbidden item attached and part of the piece of meat is inside the sauce, we say that "the piece becomes just as forbidden as a neveila". There are those that say that we don't say "the piece becomes just as forbidden as a neveila" if a forbidden liquid became mixed with a permitted liquid, and afterwards the entire thing became mixed with another permitted item; and we would only require sixty times against the [original] forbidden [liquid] that fell [in order to nullify the forbidden part of the mixture]. And there are those that rely on this in other prohibitions if it's needed in a case of great loss, but not by milk and meat. And if a dry item became mixed with a dry item, we don't say by any prohibition that "the piece becomes just as forbidden as a neveila". And see above in chapter 99 according to the law of "the piece becomes just as forbidden as a neveila". A vessel that became forbidden by absorbing a forbidden item, we do not say by it that "the piece becomes just as forbidden as a neveila", and we only need sixty times against the prohibitted item that was absorbed [in order to nullify it], and see above in chapter 98.
A drop of milk that falls on the outside of a pot that is on the fire, if [the drop] falls opposite the food [in the pot] one only needs [the amount of food in the pot to be] 60 times [the amount of milk] in the drop that was absorbed within [the walls of the pot], this is as if [the drop] fell into the food [itself]. But if [the drop] fell [opposite] a place [in the pot] where there is no food, it spreads out within the walls of the pot until it is next to the food such that there is not 60 times against the drop, that spot on the pot is prohibited, and if one stirs against the prohibited spot on the pot, the food is prohibited. This is how to fix it: do not touch it until it has cooled off. [Isserles:] This applies specifically to an old pot [one that has been used within the last 24 hours]. If [the pot] is new [has not been used within the last 24 hours], in any case one needs 60 times only against the drop that fell on it, as it says later in section 98, concerning the spoon.
The prevailing custom is to forbid when [a drop of milk] falls on the [outside] of the wall [of the pot] not opposite where the sauce is. And this is precisely when it falls on the side [of the pot] that is not near the fire, but if it fell [on the side] near the fire, it is permitted, because the fire burns it and dries it out, and then, the pot would also be permitted. And this is precisely when dealing with a small amount, such as a drop, but if a large amount fell, it is not permitted even if it fell [on the side] near the fire unless it was opposite the sauce and was sixty times the amount. Rema: And then, the pot would be forbidden even if there was sixty times the amount in the cooked food against the drip that fell, and one should immediately pour out the cooked food from it on the other side, not near the drop. And if one cooks in that pot another cooked dish, its law is the same as the first time.
There are those that permit it in extenuating circumstances, for example, on the eve of shabbat, even if [the drop] is not opposite the sauce, even not on the side of the fire, as long as there's sixty times the amount. Rema: And this is the custom. And if milk spilled, or any other hot forbidden food, on the ground, and you put on top of it a hot pot [of meat], if what spilled is not near the fire, it's only a secondary vessel [of heat], and therefore, the pot is forbidden, because it absorbs a bit, and the cooked food is permitted because the bottom item determines [the status]. And a stream from a boiling pot that went to [another] cold pot, if the stream was cut off from [the bubbles of] the boiling pot before it reached the cold [pot] it's also considered like a secondary vessel [of heat], and if it's not cut off it's like what's poured [from a primary vessel] and the cold pot is forbidden if the stream that's touching the pot is [as hot as] "when the hand retracts". And the cooked food that's inside it is permitted because what's poured only forbids up to [an amount] that needs to be peeled away. But if the [other] pot is hot, and it's a primary vessel, and certainly if it's standing near a fire, even if the stream is cold, it's all forbidden because the bottom item determines [the status]. And it's like cold inside of hot where it's all forbidden like we explained above in chapter 91. A drop that fell onto the lid of a pot, its law [is like if] it fell on the pot opposite the sauce. And this is if the pot has already begun to boil because then the steam constantly goes up and reaches the lid and goes down from there to the sauce.
A pan of milk, placed in an oven, underneath a pot of meat - the steam rises, enters into the pot, and renders it forbidden. Rema: If there was actual milk in the pan, then we require sixty times its volume in the meat. All of this is when the pan is open, and the steam rises up from the food itself, to the pan that is above it, and also if the two are so close to each other that the steam that rises is so how that it would make your hand retreat rapidly. If not, then everything is permissible. Therefore, we hang meat (slabs) over dairy pots, and we don't worry about the steam that rises. And if something is covered, then everything is permissible, since it is like two pots that touch each other, which do not make each other forbidden, and all the more so with mere steam. But ideally (lechatchila) one should be strict on all this.
A tallow candle made like a wax candle from which falls a drop [of hot, liquid tallow] on a pot, one only needs to scrape it off. However, if a drop of [hot] molten tallow fell on a pot, it requires [kashering by] immersion in boiling water.