If it is Safek dark, Safek not dark...

A case occurred in which R. Liezer was Goses on Erev Shabbos close to dark. His son Hurkanos entered to take off his father's Tefilin of his father R. Eliezer, who scolded him; he left amidst harsh reprimand.

[Hurkanos] left and screamed "woe to me - my father's mind is befuddled!''

R. Eliezer: Your mind is befuddled. My mind is not befuddled! You abandoned the Mitzvah of Ner [Shabbos], which is a Mitzvah, and [one who does it on Shabbos is] Chayav Kares, and you came to remove [my] Tefilin, which is only Reshus (to remove them at night) and is only an Isur mid'Rabanan [to put them on at night - SHA'AREI TORAS ERETZ YISRAEL. R. MEIR SIMCHAH - perhaps he did not say that there is Misah for lighting, for Isi ben Yehudah taught there is a Melachah without Misah, and we do not know which.]

His Talmidim saw that he answered with Chachmah. They entered and were asking him, and he told them correctly what is Tamei and what is Tahor.

At the end, he said "Tahor'', and his soul departed. They said "it is recognized that Rebbi is Tahor.

(R. Mana): [Obviously, we always knew that he is Tahor. The Chidush is that his Taharah] is recognized until now (he died amidst being Metaher.)

R. Yehoshua entered, removed his Tefilin, and he was hugging and kissing him and crying. He said 'Rebbi, Rebbi, the Neder is lifted! (They had excommunicated him due to the argument about the oven of Achnai.) Rebbi Rechev Yisrael u'Farashav.'

(Mishnah): One may not immerse Kelim.

Our Mishnah discusses big Kelim, but one may scheme about small Kelim [to use them] and immerse them. (It looks like he uses them to draw water, or rinses them to clean them - R. SHLOMO SIRILIYO, Terumos 2:1.)

(R. Hoshayah - Beraisa): One may fill a Tamei Kli from a pit and scheme to immerse it.

(Beraisa): If one's bucket fell into a pit, or one's Kelim fell into a pit (even if they are partially out of the water) he may scheme about them and [fully] immerse them.

Two Amora'im [argued about this] - one said that this is [even] for Kelim that became Tamei through an Av ha'Tum'ah, and the other said that this is [only] for Kelim that became Tamei [mid'Rabanan] through a Vlad ha'Tum'ah.

Question (the one who said a Vlad ha'Tum'ah, against the one who said an Av ha'Tum'ah): It needs Ha'arev Shemesh (one may not use it until Motza'ei Shabbos. He toils on Shabbos for after Shabbos!)

Answer (the one who said an Av ha'Tum'ah): The case is, he wants to use it for Chulin b'Taharah. (Ha'arev Shemesh is needed only for Terumah or Kodshim.)

(R. Yirmeyah citing R. Ze'ira citing R. Chiya bar Ashi): A clever woman rinses a cup here, a bowl here and a plate here, and it turns out that she wets the floor of the entire house [to stop dust from rising. One may not overtly wet the floor.]

(Mishnah): [When it is Safek dark] one may tithe Demai.

(R. Yosi citing R. Avahu, R. Chizkiyah citing R. Yudah bar Pazi): [Yochanan Kohen Gadol enacted Demai and coined the word] 'Demai', [for it partially] resembles something that was fixed, and [partially] resembles something that was not fixed.

(Mishnah): One may make an Eiruv, and wrap hot food [to keep it warm].

Limitation (R. Chiya bar Aba): We permit Eruvei Chatzeros, but [not] Eruvei Techumim, for they [have an Asmachta from] Divrei Torah (PNEI MOSHE on our Mishnah).