We may make an eruv with demai, with first tithe whose terumah has been taken, and with second tithe or consecrated produce that were redeemed; and Kohanim — with challah or with terumah. But not with untithed produce, nor with first tithe whose terumah has not been taken, nor with second tithe or consecrated produce that were not redeemed. If one sends his eruv with a deaf-mute, a mentally deranged person, or a minor, or with someone who does not accept eruv, the eruv is not valid. But if he instructed another to receive it from him, the eruv is valid.

If he placed it on a tree, higher than ten fists, his eruv is not valid; below ten fists, his eruv is valid. If he placed it in a ditch, even a hundred cubits deep, his eruv is valid. If he put it atop a reed or atop a pole, so long as it is uprooted and is stuck [into the ground], even if it is a hundred cubits high, his eruv is valid. If he placed it in a locker and lost the key, the eruv is valid. R’ Eliezer says: If he does not know that the key is in its place, the eruv is not valid.

If it rolled beyond the techum, or a heap fell on it, or it burned, or [it was] terumah which became contaminated — if it was still day, the eruv is invalid; if after dark, the eruv is valid. If it is in doubt — R’ Meir and R’ Yehudah say: He is caught in between. R’ Yose and R’ Shimon say: A doubtful eruv is valid. Said R’ Yose: Avtulmos attested in the name of five sages that a doubtful eruv is valid.

A person may attach a condition to his eruv and say, ‘‘If gentiles come from the east, my eruv is to the west; if from the west, my eruv is to the east; if they come from both directions, I shall go to the place I choose; if they do not come from either direc-tion, I am as my townspeople.’’ ‘‘If a scholar comes from the east, my eruv is to the east; from the west, my eruv is to the west; if one comes to here and [one comes] to there, I shall go to the place I choose; if to neither direction, I am as my townspeople.’’ R’ Yehudah says: If one of the scholars was his teacher, he must go to his teacher. But if both were his teachers, he may go to the place he chooses.