Does the salt which should be on the table when one is eating be composed of NaCl or can it be KCl?
In Shulchan Aruch OC 176; 5 writes the Rem"a, that it's a Mitzvah (i.e. a good practice - in this context) to place salt on the table since the table resembles the altar and the food offerings, and it says in the Torah that all offerings should be brought with salt. Therefore: 1. There's no obligation to have salt on ones table, yet it's a Mitzvah. 2. Only salt which can be used for the altar can be used for this purpose on the table and in the temple they used NaCl.