All meat-offerings were seasoned with salt (Leviticus 2:13). To eat salt with one is to partake of his hospitality, to derive subsistence from him; and hence he who did so was bound to look after his host's interests (Ezra 4:14, “We have maintenance from the king's palace;” King James Version marginal note, “We are salted with the salt of the palace;” Revised King James Version, “We eat the salt of the palace”).
A “covenant of salt” (Numbers 18:19; 2 Chronicles 13:5) was a covenant of perpetual obligation. New-born children were rubbed with salt (Ezek. 16:4). Disciples are likened unto salt, with reference to its cleansing and preserving uses (Matthew 5:13). When Abimelech took the city of Shechem, he sowed the place with salt, that it might always remain a barren soil (Judges 9:45). Sir Lyon Playfair argues, on scientific grounds, that under the generic name of “salt,” in certain passages, we are to understand petroleum or its residue asphalt. Thus in Genesis 19:26 he would read “pillar of asphalt;” and in Matthew 5:13, instead of “salt,” “petroleum,” which loses its essence by exposure, as salt does not, and becomes asphalt, with which pavements were made.
The Jebel Usdum, to the south of the Dead Sea, is a mountain of rock salt about 7 miles long and from 2 to 3 miles wide and some hundreds of feet high.