Take finely powdered pumice-stone and vinegar, wash the surface with the mixture, and leave it for several hours, then brush it hard and wash it clean. When dry, rub it with whiting and washleather.
Equal parts of caustic potash, quicklime, and soft soap; make into a thick paste with water, and apply with a brush; leave for about a week, and apply again and again until the stain has disappeared.
Common soda, 2 parts; pumice stone (pulverised), 1; finely powdered chalk, 1. Sift through a fine sieve, and mix with water. Rub all over the marble until the stains are removed. Then wash the stone with soap and water. Marble that is yellow with age, or covered with green fungoid patches, may be rendered white by first washing it with a solution of permanganate of potash of moderate strength, and while yet moist with this solution, rubbing with a cloth saturated with oxalic acid. As soon as the portion of the stone operated upon becomes white, it should be thoroughly washed with pure water to remove all traces of the acid.
Wash the marble thoroughly with soda and warm water to remove any grease, and apply oxalic acid by laying a piece of white cotton cloth saturated upon the spots for a short time. If it destroys the polish, repolish with oxide of tin and water applied with a cloth. If the stains are not deep, rub the surface only with the oxalic acid and water upon a small piece of cloth quickly, and wash to free the marble of acid. Then, to give it a gloss, rub with chalk wet with water.
Take a bullock's gall, 1 gill of soap lees, half a gill of turpentine; make into a paste with pipe-clay, apply it to the marble; let it dry a day or two, then rub it off, and it will appear equal to new; if very dirty, repeat the application.
Mix up a quantity of the strongest soap-lees with quicklime, to the consistence of milk, and lay it on the stone for twenty-four hours; clean it afterwards, and it will appear as new. This may be improved by rubbing afterwards with fine putty powder and olive-oil.