Leprosy in a house?

Leviticus 14 has some amazing statements, including this one:
33 The Lord spoke to Moses and Aaron, saying, 34 “When you come into the land of Canaan, which I give you for a possession, and I put a case of leprous disease in a house in the land of your possession, 35 then he who owns the house shall come and tell the priest, ‘There seems to me to be some case of disease in my house.’ (emphasis added) (ESV)


Robert Jamieson put it like this:

34-48. leprosy in a house--This law was prospective, not to come into operation till the settlement of the Israelites in Canaan. The words, "I put the leprosy," has led many to think that this plague was a judicial infliction from heaven for the sins of the owner; while others do not regard it in this light, it being common in Scripture to represent God as doing that which He only permits in His providence to be done. Assuming it to have been a natural disease, a new difficulty arises as to whether we are to consider that the house had become infected by the contagion of leprous occupiers; or that the leprosy was in the house itself. It is evident that the latter was the true state of the case, from the furniture being removed out of it on the first suspicion of disease on the walls. Some have supposed that the name of leprosy was analogically applied to it by the Hebrews, as we speak of cancer in trees when they exhibit corrosive effects similar to what the disease so named produces on the human body; while others have pronounced it a mural efflorescence or species of mildew on the wall apt to be produced in very damp situations, and which was followed by effects so injurious to health as well as to the stability of a house, particularly in warm countries, as to demand the attention of a legislator. Moses enjoined the priests to follow the same course and during the same period of time for ascertaining the true character of this disease as in human leprosy. If found leprous, the infected parts were to be removed. If afterwards there appeared a risk of the contagion spreading, the house was to be destroyed altogether and the materials removed to a distance. The stones were probably rough, unhewn stones, built up without cement in the manner now frequently used in fences and plastered over, or else laid in mortar. The oldest examples of architecture are of this character. The very same thing has to be done still with houses infected with mural salt. The stones covered with the nitrous incrustation must be removed, and if the infected wall is suffered to remain, it must be plastered all over anew.
48-57. the priest shall pronounce the house clean, because the plague is healed--The precautions here described show that there is great danger in warm countries from the house leprosy, which was likely to be increased by the smallness and rude architecture of the houses in the early ages of the Israelitish history. As a house could not contract any impurity in the sight of God, the "atonement" which the priest was to make for it must either have a reference to the sins of its occupants or to the ceremonial process appointed for its purification, the very same as that observed for a leprous person. This solemn declaration that it was "clean," as well as the offering made on the occasion, was admirably calculated to make known the fact, to remove apprehension from the public mind, as well as relieve the owner from the aching suspicion of dwelling in an infected house. (1871, public domain)


I am not sure what mural salt is, but suppose that it is a deposit of crystals, caused by a fluid containing a crystallizable substance, which fluid seeps out of a wall, and evaporates, leaving a crystalline residue.


Thanks for reading.