Yadayim, Chapter Two, Mishnah One
1) If he poured water over one of his hands with a single rinsing his hand becomes clean.
2) If over both his hands with a single rinsing:
a) Rabbi Meir declares them to be unclean until he pours a minimum of a quarter of a log of water over them.
3) If a loaf of terumah fell on the water the loaf is clean.
a) Rabbi Yose declares it to be unclean.
Section one: The person poured water over only one hand, because he intended to eat with only one hand. He also only poured one pouring, and not two. His hand is pure even if he didn’t pour the full 1/4 log because the water comes from a vessel with a pure 1/4 log. However, if the water came from a vessel with a lesser amount, his hand would not be pure.
Section two: If he tries to do this with both hands, meaning pour water over them only once, there must be at least 1/4 of a log poured over the two hands. Rabbi Meir holds that if one uses the full 1/4 log, he doesn’t need to wash off the first water that he poured onto his hands. However, if he pours water twice over his hands, then his hands are pure even if he didn’t pour a full 1/4 log as long as they came from a vessel with at least 1/4 of a log in it.
Section three: If a loaf of terumah falls on the water that he used to wash his hand, the first opinion holds that the loaf is still clean. According to this opinion the water is clean. Rabbi Yose holds that the water purified the hands, but it itself has become impure.