'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)

8680. 'And Jethro, the father-in-law of Moses, took a burnt offering and sacrifices for God' means worship springing from the good of love and the truths of faith. This is clear from the meaning of 'a burnt offering and sacrifices' as representatives of celestial and spiritual realities that belong to internal worship, 'burnt offerings' being representative of celestial realities, that is, aspects of the good of love, and 'sacrifices' being representative of spiritual ones, that is, aspects of the truth of faith, dealt with in 922, 923, 1823, 2180, 2805, 2807, 2830, 3218, 3519, 6905. The representation of 'burnt offerings' as aspects of the good of love, and of 'sacrifices' as aspects of the truth of faith, is clear from their institution - from the requirement that in burnt offerings everything was to be burnt, both the flesh and the blood, but that in sacrifices the flesh was to be eaten, as may be seen in chapters 1-5 of Leviticus; Numbers 28; and in Deuteronomy, where the following words occur,

You are to present, your burnt offerings, the flesh and the blood, on the altar of Jehovah your God; the blood of the sacrifices shall be poured out on the altar of Jehovah your God, and the flesh you shall eat. Deuteronomy 12:27.

The reason why those two realities were represented by the burnt offerings and sacrifices is that burnt offerings and sacrifices represented all worship of God in general, 923, 6905; and worship of God in general is founded on love and faith. Without these it is not worship, only ritual such as is performed by the external man who has no internal and so no life within him.