① the solubility.
Salt is easy to dissolve in the water, this is a very common phenomena.
② to moisture.
Salt of surface usually was a layer film-like of saturated salt solution by surrounded, dang this layer film solution of steam pressure below air in the steam points pressure Shi, salt on adsorption air in the of water and deliquescence; instead, dang above air in the steam points pressure Shi is rendering dry state. certainly, this just in salt was exposed in air in the is of phenomenon, closed in packaging bags in the and around air isolated of salt is not deliquescence of;
③ low freezing point
I said here is not referring to the freezing point of pure table salt (Nacl) crystals dissolving point, because in the case of no water heated to degrees Celsius to make its melting, freezing here refers to the freezing point of salt water solution, the experiment showed that, if salt water solution containing 20% of salt, it will lower the freezing point to-16 degrees centigrade.
Salt also has many other features, but explained the problem, there are some almost:) incidentally, composed primarily of frozen water--small ice crystals of snow, no matter how low the temperature, ice sublimation phenomenon of diffusion of water vapor around the snow.
When we sprinkle salt on snow, salt use its moisture absorption characteristics of adsorption of water vapor on the surface of the snow, and own more and more "tide", the layer of salt water solution film is more and more evident, I think, solution layer just a small spark to keep "invasion" of snow around, eventually colonizing all the snow wiped out!