Related for Bava Metzia 105:3

וממאי דמה שאין כן במעשר דבטיל ברובא דלמא לא בטיל כלל לא מצית אמרת הכי דלגבי תרומה חומרי דתרומה קתני קולי דתרומה לא קתני והא קא תני והן נכסי כהן

Now, what is meant by 'which is not so in the case of [second] tithes?' Surely one may deduce that a tithe is neutralised by a greater quantity [than itself]:<span class="x" onmousemove="('comment',' If a quantity of the second tithe fell into a greater quantity of hullin it is neutralised and the whole ranks as hullin, 100 times the amount being unnecessary. ');">⁷</span> but if Hezekiah's ruling is correct, it [the tithe] is an article which can become [otherwise] permitted, and whatever can become [otherwise] permitted is not neutralised even in a thousand [times its quantity]!<span class="x" onmousemove="('comment',' This is a Talmudic principle with respect to the neutralisation of an object when intermixed with permitted commodities. Though normally a certain proportion of the latter is sufficient to neutralise the former, that does not operate if the former is destined to become permitted without recourse to neutralisation. E.g., if an egg is laid on a Festival, it is forbidden on that day, but not after. Now, if this egg was mixed up with no matter how many others on the day that it was laid, it is not neutralised, and all are forbidden on that day. For since it will be permitted on the morrow in any case, the principle of neutralisation is abandoned. Now, with respect to the second tithe, which is under discussion, since, as deduced, it can be annulled by a lesser quantity than is necessary for terumah, or indeed, since it can be annulled at all, it must refer to produce that cannot be otherwise made fit. Now, the remedy for ordinary second tithe that is mixed up with hullin is either to take the whole to Jerusalem, which can be easily done, as one has to eat the rest of the second tithe there in any case, and consume it there, or redeem the quantity that was intermixed. The only case in which these remedies cannot be employed is when the second tithe was unclean, so that the whole mixture may not be eaten, and is worth less than a perutah, and so not subject to redemption. But if Hezekiah's ruling that second tithe worth less than a Perutah can be redeemed by retrospectively including it in other redeemed produce is correct, the law of neutralisation cannot operate! ');">⁸</span> — But how do you know that 'which is not so in the case of the [second] tithe' means that it is neutralised by a greater quantity [than itself]; perhaps it means that it cannot be neutralised at all?<span class="x" onmousemove="('comment',' In contradistinction to terumah, which is neutralised by 100 times its quantity. ');">⁹</span>

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