If a utensil that had yet to be immersed in a Mikveh became mixed with utensils that had been immersed, and one cannot distinguish between them, such as forks or dishes of the same set, the question arises whether these utensils require an additional immersion. Since one cannot discern between the utensil that had not undergone immersion and those that had, any utensil from the group could potentially be the one that still requires immersion. Would one be required to immerse all the utensils before using them with food?

According to some authorities, we may apply in this case the standard Halachic principle known in the Talmud as "Chad Be'trei Batil," which means that the majority in a mixture of indistinguishable items effectively negates the minority. In our case, the majority of the forks in the set are permissible for use, and one would therefore be permitted to use all the forks, even though one of them has not undergone immersion.

Others, however, including Rabbi Chayim Palachi (Turkey, 1788-1868), disagreed, claiming that the case of a utensil requiring immersion falls under the category of "Davar She'yeish Lo Matirin," items that could be made permissible. The concept of "Bittul," which allows for a forbidden item to become negated by a majority of permissible items, applies only when the forbidden status is permanent and unshakeable. For example, when dealing with a piece of non-kosher meat that becomes mixed with pieces of kosher meat, there is no mechanism by which the non-kosher meat can become permissible for consumption, and therefore the law of Bittul applies. In our case, however, one has the option of immersing all the utensils and thereby rendering them all permissible for use. In such a case, where there is a readily available means of rectifying the situation, one may not rely on Bittul, and one must therefore immerse all the utensils before using them. Rabbi Chayim Palachi rules that one would even recite a Beracha when immersing the set of utensils.

Some authorities disputed this application of "Davar She’yeish Lo Matirin" to this case. They argued that the rule of "Davar She’yeish Lo Matirin" does not apply if some action is required to render the forbidden item permissible. In the case of the immersed utensils that became mixed with non-immersed utensils, the passage of time alone will not remove the utensils’ forbidden status; an act of immersion is required. This case thus does not qualify as "Davar She’yeish Lo Matirin," and we may therefore apply the standard rule of "Bittul."

As for the final Halacha, Chacham Ovadia Yosef, in his work Halichot Olam (vol. 7, p. 276), distinguishes between different kinds of utensils. When dealing with a set of metal utensils, which require immersion on the level of Torah obligation, one should be stringent and immerse the entire set if one of the utensils has not undergone immersion. However, no Beracha would be recited over this immersion. In cases involving glass utensils, which require immersion only on the level of Rabbinic enactment, one may rely on the rule of Bittul and use all the utensils without immersion.

Summary: If a utensil that has yet to undergo immersion mixes with other utensils that had been immersed, and one cannot tell the utensils apart, then in the case of metal utensils one must immerse the entire set without reciting a Beracha. If this occurred with glass utensils, one may use them even without immersing them.