Machshirin 5:10-11

Machshirin 5:10

If a person pours from a (ritually clean) hot liquid into a (ritually unclean) hot liquid, from a (ritually clean) cold liquid into a (ritually unclean) cold liquid, or from a (ritually clean) hot liquid into a (ritually unclean) cold liquid, the liquid in the upper vessel remains clean. If he pours from a (ritually clean) cold liquid into a (ritually unclean) hot liquid, the liquid in the upper vessel is rendered unclean (because of the steam). Rabbi Shimon says that even when pouring from hot to hot, if the liquid in the lower vessel is hotter, it will render the liquid in the upper vessel unclean.

Machshirin 5:11

Let’s say that a woman with ritually clean hands was stirring a ritually unclean pot on the fire. If her hands sweat, they are rendered unclean. If she had ritually unclean hands and was stirring a ritually clean pot and her hands sweat, the pot is rendered unclean. Rabbi Yosi says that the pot is only rendered unclean if her hands dripped. If one weighs grapes in the pan of a scale, the juice exuded into the pan remains ritually clean until he pours it into a receptacle. This is comparable to the situation with dripping baskets of olives or grapes.