Siman - Shabbos Daf 80

• Writing is considered the hanacha

The Mishnah stated that one is liable for carrying ink in a reshus harabim, if it is in the amount that two letters can be written with it. Rava said that if one took out enough ink that one can write two letters with it, but instead of placing the ink down in reshus harabim, he wrote two letters in reshus harabim on his clothes while he was walking (Rashi), he is liable for the transfer. The kesiva, the writing, is considered the hanacha, the placing down of the ink.

But if he took out enough ink to write one letter and wrote a letter, and then took out another amount of ink for one letter and wrote a letter, he is exempt, because the two half-measures do not combine. The reason is, that at the time he took out the last letter, the first letter had already begun to dry and decrease in volume. Therefore, the two letters no longer combine to form a full measure.

• Combining two half-measures eaten in two separate domains

It says in a Mishna earlier (76b) that one is liable for carrying food out into a reshus harabim, if it is the amount of a גרוגרת (dried fig). It was taught in a Baraisa that if one took out the equivalent of a חצי גרוגרת (half a dried fig) and he then went back inside and took out another equivalent of a חצי גרורגת, and he did so בהעלם אחד (in one lapse of awareness), then he is liable for one chatas offering. However, if he did them בשתי העלמות (in two separate periods of unawareness), then they do not combine, and he is exempt.

Rebbe Yose says that even if the two acts were carried out in the same lapse of awareness, he is only liable if he took them out to the same reshus. If he took them out into two separate reshus harabims, the two half-measures do not combine, and he is exempt from bringing a chatas.

• Darking plaster as a sign of mourning over Yerushalayim

It was taught in a Baraisa that after the Churban, the Rabbonim forbade one from plastering his house with lime, unless he mixed straw or sand into the plaster.

- Rashi explains that mixing the straw or sand into the plaster, would darken the lime, which would be a sign of mourning for Yerushalayim.

Rebbe Yehudah says that mixing in straw is permitted, but sand is prohibited because it strengthens the plaster which offsets the detrimental loss of its whiteness.