The following method of cleaning engravings has been found effective whenever dirt and faint stains were to be removed, though probably it is not so efficient as the chloride of lime process (described on p. 206) in dealing with stains of long standing. The specimen to be cleaned should, if possible, first be detached from its mount. Lay it face upwards on a clean, smooth board in the sink, or similar place, and sprinkle it with ordinary salt till thinly covered. Then take a lemon, cut it, and squeeze the juice over the engraving so as to dissolve the greater proportion of the salt. Then raise one end of the board to slant at an angle of about 25 , and flood it with nearly boiling water until all the salt and lemon juice are washed away. Drying must be allowed to proceed spontaneously.