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ANSWERS TO REVIEW QUESTIONS

prepared by Rabbi Eliezer Chrysler
Kollel Iyun Hadaf, Jerusalem

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Shabbos 20

Questions

1)

(a) Meat, onions and eggs must be roasted 'ke'Ma'achal ben Derusai' - one third of their cooking time.

(b) ben Derusai was an infamous robber who would eat his meat etc. one third done.

(c) This leniency applies to cooking, too.

(d) Food that has been cooked is not subject to 'Bishul Akum', and that begins from the time the food is cooked 'ke'Ma'achal ben Derusai'.

2)
(a) When Rebbi Eliezer says in our Mishnah that bread may be left in the oven from the moment that the bottom has crusted, what did he mean by the bottom, the side that sticks to the wall of the oven, or the outside of the bread that faces the air?

(b) The Gemara concludes that he is referring to the side that sticks to the wall of the oven, a Chumra, since it is the outside of the bread, which faces the flame, that bakes first.

(c) The Gemara only permitted leaving a kid-goat in the oven to roast, when it has been cut-up, and the air will interfere with the roasting, but not when the kid is still whole.

3)
(a) We do not suspect that the Kohanim will stoke the coals on Shabbos, because of the principle 'Kohanim Zerizim Hen'.

(b) "Lo Seva'aru Eish be'Chol Moshvoseichem" comes to teach us, that, although the Kohanim are not permitted to light the fire in Meduras Beis ha'Mokad (which is included in 'Moshvosei*chem*' - belonging to the people) on Shabbos, they *are* permitted (and even obligated) to burn the limbs that have been left over from the Friday Korban (since this is not included in 'Moshvosei*chem*' - since the Chalavim are the property of Hashem).

4)
(a) When Rav permits lighting a fire on Erev Shabbos only if the flame has taken 'be'Rov Kol Echad ve'Echad', he means that the majority of each log has to be alight.

(b) According to Shmuel, it will suffice if one no longer needs to say 'Bring more wood to place underneath the burning logs' - to ensure that the fire does not go out.

(c) By a solitary log of wood, some say that one requires the majority of its thickness to be alight before Shabbos enters, whereas others require the majority of the circumference. The Gemara therefore concludes, that we need both.

(d) Some interpret "ve'ha'Ach" to mean a willow tree, or willow wood. Others explain it to mean a pile of burning wood (from the root 'Ach' - brother, because the one piece burns the other.

5)
(a) When canes have been tied together, the fire has difficulty in igniting them, and consequently, in spite of their flammability, they require a majority to be lit before Shabbos.

(b) Similarly, date-pits require a majority, when they are pressed tight in a box, because then, due to their compactness, the flame cannot get to them.

(c) Rav Chisda maintains quite the opposite to be true. Under normal circumstances, according to him, the canes and the pits scatter and will therefore not ignite each other; whereas if the former is tied and the latter placed in a box, they *will*.

(d) Rav Kahana agrees with Rav Huna, making it Halachah.

20b---------------------------------------20b

Questions

6)

(a) A Madurah is a bonfire. A bonfire of pitch, sulfur, cheese or wax do not require a majority to be lit before Shabbos, because the fire burns them quickly.

(b) The Beraisa adds straw and stubble to the list.

(c) If a wick dipped in oil (which burns well) requires the majority to be lit, then how much more so - twigs!

(d) 'Shucha de'Arza' is the woolly substance that is found between the bark and the trunk of a willow tree. 'Zaza' is moss. Neither requires a majority.

Hadran Alach, Yetzi'os ha'Shabbos'.

Perek Bameh Madlikin

7)

(a) 'Shucha de'Arza' is the woolly substance between the bark and the trunk of the tree (as we just learnt at the end of 'Yetzi'os ha'Shabbos).

(b) The Gemara first thought that flax shavings are what the Mishnah calls 'Chosen', which is one of the Pasul wicks listed in our Mishnah. It concludes however, from a Pasuk in Yeshayah, that flax shavings and Chosen are two different things, and that, in fact, the former are not fit (technically - see Tosfos Yeshanim, quoted in the left-hand margin) to use as wicks.

(c) 'Kisna de'Dayek ve'Lo Nafitz' is flax that has been combed but not spun, which is why the oil does not run up the wick (although this is not the reason given by the Gemara later for the Pasul wicks - see 21a, answer 1b).

(d) 'Shira'im' is a silk coat. 'Shira Parnada' or 'Gushkera' is a coat made of the waste of silk.

8)
(a) 'Pesilas ha'Midbar' is the woolly substance found between the bark and the trunk of a willow tree, that we already explained above (at the end of Amud Aleph).

(b) 'Pesilas ha'Midbar' is the name of a certain type of tall grass that grows in the desert.

(c) 'Yerokah she'Al Penei ha'Mayim' is barnacles that one finds growing on the sides of a ship. It cannot be the moss that floats on the surface of the water, because that tends to just break up, and is not fit to be used as wicks.

(d) The reason that the above are all Pasul as wicks, is because they do not suck up the oil, as good wicks tend to do.

9) Our Tana includes neither wicks made of wool - because the flame jumps, nor those made of hair - because the fire merely singes them, but does not create a flame.

10)

(a) The reason that the Beraisa needed to inform us that, until now, our Tana has been dealing with Pasul wicks, and that, from now on, he will deal with Pasul oils (even though this appears obvious), is in order to make it clear, that although wax is Pasul to be used as an oil, it is not included in the Pasul wicks - i.e. to use it in the way that we do - in the form of candles.

(b)

1. ... 'Zefes' is the pitch.
2. ... 'Sha'avah' is bee's wax - the waste of honey.
3. ... 'Itran' is the waste of pitch (a liquid that oozes from the wood (after the pitch has been extracted), when one applies heat.
(c) It is important to know that 'Itran' is another name for 'Pesulta de'Zifta' and 'Sha'avah', for 'Pesulta de'Duvsha' - for buying and selling purposes - e.g. that if someone purchases 'Itran' or 'Sha'avah', one may supply him with 'Pesulta de'Duvsha' or 'Pesulta de'Zifta' , respectively.
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