4:7. We now move to a new topic, one that will accompany us through many mishnayos until the end of the next chapter: the laws of meduma - a mixture containing Terumah or terumas maaser (the law is the same for both) together with chullin.
Defining the mixture:
A mixture of min b'mino is a mixture of two things of exactly the same kind, such as figs with figs or grape juice with grape juice - as opposed to apple juice that became mixed with grape juice, which is not min b'mino but two different kinds. Within a mixture of min b'mino we must distinguish between two situations:
Dry with dry - the individual pieces are not absorbed into one another. For example, grapes some of which are Terumah and some chullin: each grape is a unit unto itself, and one can lift a single grape out of the pile without its having merged with its fellows.
Liquid with liquid - liquids that blend into one another. For example, grape juice of Terumah that became mixed with grape juice of chullin: every cup drawn from the mixture contains a bit of the chullin and a bit of the Terumah.
The ordinary rule of nullification in a mixture:
By Torah law, in both cases a simple majority suffices to permit the forbidden component. A forbidden grape that fell into two permitted grapes - all three grapes are permitted. The Rema rules that they may not be eaten all at once in a single swallow, since then the forbidden item is certainly being consumed, but rather one after another.
In a liquid mixture, by rabbinic law a majority does not suffice; rather, sixty times as much permitted substance is required against one unit of the forbidden substance: forbidden grape juice that fell into permitted grape juice requires sixty times as much permitted juice to nullify it.
The special stringency of Terumah:
In a mixture containing Terumah, called meduma, the Sages were even more stringent. Terumah is not a forbidden food of the general sort, since a non-kohen who eats it is liable to death at the hands of Heaven, and therefore the Sages raised the bar: sixty parts of permitted substance against the unit of forbidden substance do not suffice, but rather one hundred parts against one are required.
To be precise: terumas maaser is one percent of the quantity. If there were one hundred grapes and one of them was separated as terumas maaser, and then fell back in among them - we have one forbidden grape against ninety-nine permitted ones, and by all opinions this is a forbidden meduma mixture. Likewise by all opinions, one hundred permitted grapes against one forbidden grape permit the mixture, and it is enough to remove one grape and give it to a kohen. The Tannaim in our mishnah disagree as to whether a full hundred against one is required, or whether slightly more than ninety-nine suffices, and there are three views on the matter:
"Terumah olah b'echad u'meah" - the view of Rabbi Eliezer, and this is the practical halachah. To nullify the Terumah, one hundred and one are required in total: one unit of Terumah mixed into one hundred units of chullin. Such a mixture is no longer forbidden, and one unit is removed from it and given to a kohen because of his monetary claim on that unit, for it was his and it is called "the property of the tribe" - an asset belonging to all the kohanim. The remaining hundred are eaten as they are.
"B'meah v'od" - the view of Rabbi Yehoshua. A full hundred and one is not needed; it suffices that the mixture contain slightly more than a hundred. Ninety-nine against one, which is one hundred in total - forbidden; but slightly more than ninety-nine against one - permitted. One unit is removed for the kohen, and the remaining ninety-nine and a bit may be eaten by a non-kohen. And that additional amount of "v'od" - it has no fixed measure, and any addition at all beyond ninety-nine suffices.
"Kav l'meah se'ah" - the view of Rabbi Yose ben Meshulam. The "v'od" is not some tiny amount, but a fixed measure: a kav per hundred se'ah, which is a sixth, in the language of the mishnah "shtus hameduma" - a sixth of the total quantity. That is, ninety-nine and a sixth of chullin are required against one unit of Terumah in order to permit it.
Calculating "a kav per hundred se'ah":
A se'ah is about twelve liters, and it is convenient to picture it as a case of six two-liter bottles, while the kav is like a single two-liter bottle, that is, a sixth of a se'ah. It turns out that an addition of a kav, a sixth, is required on top of the hundred se'ah: one hundred units of se'ah require one hundred and a sixth in total, meaning one se'ah of Terumah mixed into ninety-nine and a sixth units of chullin, and then the entire mixture is permitted according to Rabbi Yose ben Meshulam.
The practical halachah:
The Yerushalmi rules like the last opinion, but the Rema, the Shulchan Aruch, and likewise the anonymous Mishnayos and the Babylonian Talmud all follow the opinion of Rabbi Eliezer that one hundred times is required. Therefore, in all the coming lessons dealing with mixtures and medumma we will always assume that one hundred parts of chullin are needed against a single unit of Terumah for the mixture to be permitted, and anything less than one hundred times leaves the mixture forbidden.
How a mixture is handled in practice:
If there are one hundred and one units in all - one of Terumah and one hundred of chullin - one unit is removed and given to a kohen, and the remaining hundred may be eaten. But if there were only ninety-nine and one unit of Terumah fell in, making one hundred in all, none of the medumma mixture may be eaten, since every part of it carries the concern of the prohibition, and the entire hundred must be given to a kohen. Nevertheless, one may sell the ninety-nine units to the kohen, for financially he owes him only one unit: if the going price of a fig is a shekel, and the mixture contains one hundred figs, he sells the kohen all one hundred for ninety-nine shekels only, since he may not charge him for that one fig which is Terumah and belonged to him in any case.