Glycerine, castor oil, and mineral oil are suitable;€.8. 15 per cent arachis (ground nut) oil, 15 per cent sperm oil, 70 per cent mineraloil.

Any ordinary light machineoil will do, but regular typewriter or spermoil is best. Apply it sparingly—as much aswill cling to the end of a toothpick will do—and wipe off all excess.