On Shabbos 76B regarding the requirement to separate Chalah, you write (Background to the Daf) that we separate Chalah with a Berachah only for dough made from the volume of 43.2 Beitzim of flour (about 10 1/2 cups or 2.48 liters). An amount about half that much requires Chalah to be separated without a Berachah.
I am curious about your calculation. I think that R. Chayim Na'eh considers a Beitzah to be about 2 fluid ounces or 57 milliliters, so 43.2 eggs comes out to your Shi'ur with a Berachah, the Chazon Ish Shiur would be about 70% bigger. My Sidur and Rav say to separate on 1.2 Kilos without a Berachah, and 2.25 Kilos with a Berachah I have measured several times, always getting about 7 cups per kilo, we don't make a Berachah on less than 16 cups!
My questions therefore are as follows:
1. Why separate for half that amount without a Berachah? We should not separate for less than that amount at all!
2. Why do we give a Shiur in weight and not volume? The Shiur given by Chazal is in volume!
Pesach Feldman, Jerusalem, Israel
A kilo of flour is a measure of weight, not volume. When it comes to water, we can use the kilogram as a measure of volume, since by definition a gram is the weight of 1 milliliter of water; thus a liter weights 1 kilogram.
Flour is lighter than water so a kilogram of flour has a much greater volume. The Rishonim say it is 1/3 lighter; today's flour seems to be half the weight of water. This makes the R' Chaim Na'eh shiur 1.25 kilo and the Chazon Ish shiur about 2.2 kilo of flour.