509. Sodom Salt

Brachos 6:3

Washing hands between courses is optional: one may do so – or not – as he desires. There is no need to wash before or after eating unconsecrated fruit. Quite the opposite, doing so is seen as a sign of arrogance. When bread is eaten with salt, one must wash his hands after because of Sodom salt, or salt similar to Sodom salt. Touching one’s eyes with this on his hands could cost one his vision. Soldiers in an army camp need not wash before eating because they are occupied with battle but they must still wash after eating because of the health issues.

Brachos 6:4

One's hands must be washed to the wrist using at least a revi'is of water (a little more than three ounces) per two hands. Anything that would be considered an interposition between a person and the water of a mikvah is also an interposition when it comes to washing hands. Any liquid that counts towards the volume of a mikvah also counts towards the revi’is needed for hand-washing.