Sublimation

Few substances such as iodine, ammonium salts, naphthalene can sublimate,. Sublimation may be used if any substance is contaminated or spoiled by any of the sublimates.

The mixture is taken on a watch glass & a funnel is held over it in the inverted position. The mixture is then heated. The sublimate can be sublime and will solidify again in contact with inverted funnel held above. Thus the 2 substances will be separated.