'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)

1864. That 'on that day Jehovah made a covenant with Abram' means the joining together of the Lord's Interior Man and His Internal Man is clear from the meaning of 'a covenant' as a joining together, dealt with already in 665, 666, 1023, 1038. Here, because in the internal sense the Lord is the subject, it means an interior conjunction. For the Lord advanced more and more towards conjunction and union with Jehovah His Father, till at length He became one, that is, the Human Essence itself also became Jehovah, who was the Lord's Internal itself. These things were represented by 'the covenant which Jehovah made with Abram'. Anyone may see that Jehovah never makes a covenant with man, for such would be contrary to the Divine. What is man but something base and filthy, which of itself thinks and does nothing but evil? All the good that he does comes from Jehovah. From this it becomes clear that this covenant, like every other covenant made with Abram's descendants, was nothing else than a representative of the Divine and of the heavenly things of the kingdom of God. This particular covenant made with Abram was a representative of the joining together of the Lord's Human Essence and His Divine Essence, that is, Jehovah. That it was a representative of the joining together of the Lord's Interior Man and His Internal Man, that is, Jehovah, is clear from what has gone before - that the Lord joined and united Himself more and more through the conflicts brought about by temptations and through victories. What the Interior Man was has been stated already, namely that which was between the Internal and the External.