'Salt' symbolizes the desire of truth and good to be conjoined with each other. So, a salt can conjoin water, which corresponds to truth, with oil, which corresponds to good.

Salt can also have a negative meaning. 'Lot's wife becoming a statue of salt' signifies all the good of truth being vastated, or laid waste, in the church that Lot represented. In that story, Lot's wife represented a form of 'truth' that turned itself away from 'good,' and looked instead to doctrinal matters. Because 'salt' can signify vastation, and 'cities' signify doctrinal aspects of truth, in old times they sowed cities with salt when they were destroyed to prevent them from being rebuilt, as in Judges 9:45

(References: Arcana Coelestia 10300)

10055. 'A fire offering to Jehovah' means all things springing from Divine Love. This is clear from the meaning of 'a fire offering to Jehovah' as that which springs from Divine Love; for 'fire' in the Word means love in both senses, and when used in reference to Jehovah or the Lord it means Divine Love. For the meaning of 'fire' as love in both senses, see 4906, 5215, 6314, 7324; and for its meaning - in the highest sense, in which Jehovah or the Lord is the subject - as Divine Love, 6832, 6834, 6849. A burnt offering is called 'a fire offering to Jehovah' because when the Divine took on the Human, from that Human fought against and subdued the hells, and at the same time united it to the Divine, in order to save the human race, He did so out of pure love. That uniting is meant by a burnt offering, see 10042, 10053.