A Matter Of Definition
Oil Set Apart For One Minchah Is Invalid For Another’
(Menachos 79b)
A standard minchah offering consists of a log of oil, an issaron of flour, and a kometz of levonah. These ingredients are placed in a sacred vessel after which a kohen then scoops out a portion of flour and oil with his three middle fingers. This act is called kemitzah.
Kemitzah and Designation
R. Yochanan says kemitzah establishes the minchah as one indivisible entity. Thus, if some flour (or oil) is lost after kemitzah is performed, it may not be replaced with other flour. However, if some flour was lost prior to kemitzah, it can be replaced with new flour from one’s home.
The Chazon Ish (Novella, 19:24) points out that R. Chisda on our daf rules that oil designated for one minchah is invalid for another minchah. If so, he asks, why does R. Yochanan permit replacing lost flour prior to kemitzah? Since the oil of that minchah was designated with the original measure of flour, it should be invalid for use with new replacement flour.
Defining Minchah
The Mikdash David (Novella, 10:1) argues that “minchah” does not refer to the originally-sanctified flour with oil. Rather, it refers to an abstract obligation. Thus, all R. Chisda meant is that oil designated for one type of minchah (or minchah obligation) may not be used for another. For example, oil designated for a minchah machavas (a shallow-pan minchah) may not be used for minchah marcheshes (a deep-pan minchah). Similarly oil designated to fulfill a particular pledge may not be used for another pledge.
What R. Yochanan permits, though, is replacing flour lost prior to kemitzah with other flour. That is not problematic since both the oil and new flour are being used for the same type of minchah and same obligation.