['The mishnayot that follow list those materials in which such a pot may be insulated on Shabbat eve and those materials in which it may not be insulated.
In what may one insulate a pot of cooked food on Shabbat eve, and in what may one not insulate it? One may neither insulate it in the solid residue of produce that has been pressed free of its oil, nor in manure, nor in salt, nor in lime, nor in sand, whether those materials are moist or whether they are dry. All of these materials spontaneously generate heat when piled for an extended period. Therefore, they add heat to a pot insulated in them. And one may neither insulate a pot in straw, nor in the residue of grapes that have been pressed for their juice, nor in soft material, e.g., from tattered clothing, nor in grass, when these materials are moist. However, one may insulate a pot in them when they are dry. One may insulate a pot of hot food on Shabbat eve in clothing, in produce, in doves’ wings, in a carpenter’s wood-shavings, and in the chaff of fine flax. Rabbi Yehuda prohibits doing so when it is fine, and permits doing so when it is coarse.', 'One may insulate cooked food on Shabbat eve in animal hides and may move those hides on Shabbat. So too, one may insulate food in wool fleece and, in contrast to hides, one may not move the fleece.How, then, does one act if he insulated food in fleece, and now wishes to remove the pot? He lifts the cover, which he is permitted to move, and the fleece falls by itself. He need not even touch it. Rabbi Elazar ben Azarya says: If he placed the pot in a basket filled with fleece, he leans the basket on its side so that the fleece will fall to the side and takes the pot. Otherwise, there is concern lest the wool collapse when he lifts the pot from the basket. And then, he will be unable to replace the pot, as it is prohibited to move the wool to make room for the pot, since the wool is set-aside. And the Rabbis disagree and say: He may take the pot and afterward replace it. If one did not cover a pot of cooked food on Shabbat eve while it was still day, he may not cover it after dark. However, if one covered it while it was still day and it was uncovered on Shabbat, he is permitted to cover it even on Shabbat. One may fill a jug with cold water on Shabbat and place it beneath a pillow or a cushion to prevent it from getting warm.']