daf bit: Eruvin 104

The mishna teaches that on Shabbat, salt may be scattered on the altar's ascent (which is a smooth surface) so that the priests will not slip (e.g. after a rain when that smooth surface is slippery). In the g'mara R. Ika of Pashronia points out: this means only in the Temple may this be done and not in the country, but elsewhere we have learned that if a courtyard floor is damaged by rainwater one may bring straw and level it. How do we reconcile these, he asks? Straw is different because the owner does not renounce it; he intends to collect it later for other uses. To explain further (per a footnote): the scattering of materials on the ground is forbidden on Shabbat as a form of building; however, scattering of temporary materials doesn't count. The salt, on the other hand, is a permanent addition, so it requires a specific exemption for the purpose of the operation of the Temple. (104a)

Quite aside from the primary content, I learned from this that salt as an antidote to slick surfaces is way older than I thought.

(This is the penultimate daf in this tractate. Next week, on to Pesachim!)