Terumot, Chapter Ten, Mishnah Eight
This mishnah deals with brine that comes from a barrel in which unclean fish were mixed with clean fish.
Unclean fish which was pickled with clean fish:
1) If the jug contains two seahs and the unclean fish weighs ten zuz in Judean measure, which is five selas in Galilean measure, the brine is forbidden.
2) Rabbi Judah says: it needs be a quarter [of a log] in two seahs.
3) Rabbi Yose says: one-sixteenth of it.
Section one: We have to pay careful attention to the measurements being mentioned here. The jug contains two seahs, which is equivalent to 48 logs. There are ten zuz of unclean fish in Judean measure which is equivalent to five selas in Galilean measure, which equals twenty zuzJudean zuz are twice the size of Galilean zuz. In two seahs there are 9,600 Judean zuz (each log has 200 zuz). So if 1/960 of the mixtures volume is unclean fish, the brine is prohibited.
Section two: One quarter of a log is equivalent to 50 zuz. So if there are 50/9600 (=1/192) parts unclean fish, Rabbi Judah holds that all of the brine is forbidden.
Section three: Rabbi Yose says that the unclean fish must be 1/16 of the whole jug before the brine becomes forbidden. This means that unless there are three logs of unclean fish (600 zuz), the brine is still permitted. His is by far the most lenient opinion. The first opinion forbade at ten zuz, and Rabbi Judah at fifty zuz.