As salt and sugar are both water soluble, another way to separate them
may be to dissolve the mixture in water, then make a water insoluble
derivative of the sugar, such as the pentaethyl glucoside. The
derivative should crystallize out of the water solution. Remaining
traces of dissolved glucoside could be extracted from the salt water
using ether. The sugar can be regenerated from the glucoside once the
separation is complete.