Responsa על שבת 200:1

Vinegar that has been mixed with the yeast of beer must be sold to a Gentile before Passover (in order not to violate the commandment of Ex. 12,19 and 13,7, which prohibits a Jew from possessing leaven during the Passover week). The Gentile may be told that if he holds the vinegar until after Passover, a Jew will buy it from him.
SOURCES: Cr. 68; Pr. 31; L. 340; Rashba I, 850.

On the Sabbath, a Jew is not permitted to pour sewage into a stone-trough, which is situated partly in his yard and partly in the public domain (used to carry off sewage into the street), unless the trough is covered for four cubits length in the public domain.
SOURCES: Cr. 69; Pr. 31; L. 341; Rashba I, 850; Mord. Shabb. 375.

Q. On the Sabbath, may a Jew use latrines which are built in the city wall and open into a ditch surrounding the wall, so that the feces falling into the ditch are moved (by his force) from one Sabbath domain into another?
A. He should fasten a board beneath the seat (within not more than three tefahim below the latrine walls) so that the feces first fall on the board and then into the ditch. Should the board break on the Sabbath, he would still be permitted to use the latrine on that day.
SOURCES: Cr. 178, 179; Pr. 96; L. 349; Mord. Shabb. 376; Hag. Mord. Shabb. 461; Tashbetz 38; Hag. Maim., Shabbat 15, 4; Kol Bo 31 (p. 34a). Cf. Terumat Hadeshen 66.