1. Place the mixture of naphthalene and sand in a sublimation apparatus, which consists of a heated bottom chamber and a cooled upper chamber.

2. Heat the bottom chamber to a temperature that is high enough to sublime naphthalene (around 80°C), but not so high as to decompose it. Naphthalene will sublime and turn into a vapor, leaving the sand behind.

3. The naphthalene vapor will condense on the cooled surface of the upper chamber, forming solid crystals.

4. Collect the sublimed naphthalene crystals from the upper chamber.

Note: This method is based on the different sublimation points of naphthalene and sand. Naphthalene sublimes at a lower temperature compared to sand, allowing for their separation.

Another option is to use solvent extraction. Because sand is insoluble in most solvents, you could dissolve the naphthalene in a suitable solvent, such as ethanol or hexane. Then, you could filter the mixture and evaporate the solvent to recover the naphthalene.