Reference for Bava Kamma 230:11

לאו איתמר עלה א"ר סימון אריב"ל לא שנו אלא שלא טרקו אבל טרקו אסור

— He may make it good by using a strainer, in accordance with the view of R. Nehemiah as taught: A strainer<span class="x" onmousemove="('comment',' I.e., liquid poured therein to be strained. ');">²⁸</span> is subject to the law of uncovering;<span class="x" onmousemove="('comment',' For the venom, if any, will pass through the strainer. ');">²⁹</span> R. Nehemiah, however, says that this is so only where the receptacle underneath was uncovered, but if the receptacle underneath was covered, though the strainer on top was uncovered the liquid [strained into the receptacle beneath] would not be subject to the law of uncovering as the venom of a serpent resembles a fungus and thus remains floating in its previous position.<span class="x" onmousemove="('comment',' In the strainer without passing on to the receptacle underneath (Tosef. Ter. ibid. 14.) ');">³⁰</span>

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