What substanes can melt ice the fastest?

A very good substance for melting ice is table salt. This is because salt is highly soluble in water, and, as more NaCl dissolves in the water, the more this impurity will depress the melting point. Because the water's melting point will be depressed, it will start to melt above zero degrees Celsius.

(I'm not sure this is the best substance to melt ice, I simply put it here because of its solubility in water; if anyone knows a more soluble salt, then that will probably melt ice better) Sand is also really good to melt ice