Note: The following is a question, an answer, a follow-up question and a follow-up answer
Recently I had a conversation with a Jordanian brother about the role of knowing local culture to understanding the Bible. He gave me an example and said that the Jordanians put salt on fire to increase the temperature of the rocks for baking bread. At some point it loses its ability to be useful in this way and is taken away and thrown onto the path, just as Jesus spoke of in Matt 5:13. However, I cannot find any source that confirms this or any scientific information about salt losing its saltiness. Any thoughts?
Let me get you started: Let me know if this is sufficient, as I can find more material for you.
I am pulling the following material from the internet because I am not an expert on the kind of salt used in Palestine.
It should be stated in this connection that the salt used in this country is not manufactured by boiling clean salt water, nor quarried from mines, but is obtained from marshes along the seashore, as in Cyprus, or from salt lakes in the interior, which dry up in summer, as the one in the desert north of Palmyra, and the great lake of Jebbul, southeast of Aleppo.
"Maundrell, who visited the lake at Jebbul, tells us that he found salt there which had entirely ‘lost its savor,’ and the same abounds among the debris at Usdum, and in other localities of rocksalt at the south end of the Dead Sea. Indeed, it is a well-known fact that the salt of this country, when in contact with the ground, or exposed to rain and sun, does become insipid and useless. From the manner in which it is gathered, much earth and other impurities are necessarily collected with it. Not a little of it is so impure that it cannot be used at all, and such salt soon effloresces and turns to dust – not to fruitful soil, however. It is not only good for nothing itself, but it actually destroys all fertility wherever it is thrown; and this is the reason why it is cast into the street. There is a sort of verbal verisimilitude in the manner in which our Lord alludes to the act: ‘it is cast out’ and ‘trodden under foot;’ so troublesome is this corrupted salt, that it is carefully swept up, carried forth, and thrown into the street. There is no place about the house, yard, or garden where it can be tolerated. No man will allow it to be thrown on to his field, and the only place for it is the street, and there it is cast to be trodden underfoot of men."
Clarke’s Commentary on the Bible
Ye are the salt of the earth – Our Lord shows here what the preachers of the Gospel, and what all who profess to follow him, should be; the salt of the earth, to preserve the world from putrefaction and destruction. See the note on Leviticus 2:13.
But if the salt have lost his savor – That this is possible in the land of Judea, we have proof from Mr. Maundrell, who, describing the Valley of Salt, speaks thus: "Along, on one side of the valley, toward Gibul, there is a small precipice about two men’s lengths, occasioned by the continual taking away of the salt; and, in this, you may see how the veins of it lie. I broke a piece of it, of which that part that was exposed to the rain, sun, and air, though it had the sparks and particles of salt, Yet It Had Perfectly Lost Its Savour: the inner part, which was connected to the rock, retained its savor, as I found by proof." See his Trav., 5th edit., last page. A preacher, or private Christian, who has lost the life of Christ, and the witness of his Spirit, out of his soul, may be likened to this salt. He may have the sparks and glittering particles of true wisdom, but without its unction or comfort. Only that which is connected with the rock, the soul that is in union with Christ Jesus by the Holy Spirit, can preserve its savor, and be instrumental of good to others.
To be trodden underfoot – There was a species of salt in Judea, which was generated at the lake Asphaltites, and hence called bituminous salt, easily rendered vapid, and of no other use but to be spread in a part of the temple, to prevent slipping in wet weather. This is probably what our Lord alludes to in this place. The existence of such a salt, and its application to such a use, Schoettgenius has largely proved in his Horae Hebraicae, vol. i. p. 18, etc.
Thanks for putting these sources together. I had read most of what you sent in our computer program for Word Search. When I spoke with scientists, however, my sources claim that salt is salt and that it never loses its savour. If that is true, perhaps it diffuses due to heat and then is useless. So I guess I have 2 questions:
1. Does salt really intensify a fire? There must be some reason for the bedouins to use it on their fires.
2. How does salt lose its saltiness?
I turned to you because I know you have the science resources to find an answer.
As a chemist, I think arguments about salt literally losing its saltiness really do not make much sense. Sodium chloride is one of the three or four most stable compounds in the world!! Virtually no natural reaction can cause salt to turn into any other compound. Just last week in my chem class I told my students that there is literally no chemical reaction which can turn sodium ions in salt into anything else—that we must use electrolysis to extract sodium metal from sodium ion.