How did they prepare the anointing-oil?
Rashi #1 (citing R. Meir in Kerisus, 5a): They boiled the spices directly in the Hin (twelve Lugin) 1 of oil. 2
Rashi #2 (citing R. Yehudah, Kerisus, 5a): They soaked the pounded spices in water - to prevent them from absorbing the oil, and boiled them in oil until it absorbed the fragrance of the spices, 3 at which point they skimmed it off the top.
Corresponding to the twelve tribes (Targum Yonasan). Moreover, the Gematriyah of "Zeh" in Pasuk 31 is 12 (Rashi).
R. Yehudah queries R. Meir in that one Log of oil was not nearly sufficient to boil all the spices - to which R. Meir replied that it was a miracle (See Kerisus, 5a).
See Ramban (citing a Yerushalmi) and Seforno, who present slightly different ways in which this procedure was carried out.
