To clean a microscope that has become rusty through lying in a damp place, well rub the affected parts with paraffin. If the spots are merely superficial the paraffin will fetch them off; but if the damp has penetrated deeper, the only remedy is to remove the entire coating of Lacquer, re-polish the metal, and re-lacquer. To do this, remove the lenses, take the microscope to pieces, and boll the lacquered parts with a handful of strong soda in water. This will remove every trace of the old lacquer. When dry, with some No. 1 blue-black emery paper grain the pieces as before. The old graining will give the direction. When all the pieces, screw-heads, etc., have been separately grained, they must be separately heated and lacquered. The draw tubes, if stained, need only be cleaned up with paraffin; but if it is thought desirable to paper them also, they must not he lacquered, hut should be rubbed over with vaseline instead.