If grease is apparent, it should first of all be removed, as its presence will interfere with some of the subsequent processes. With this object, the leaf must be laid perfectly flat on a sheet of glass and the grease marks damped out with a pad of cotton wool moistened with benzine. Rubbing is never resorted to; the spots must be merely patted over and over again until they disappear, which they will do after a time. Sometimes the text itself will vanish as well, but whether it will do so or not depends upon the character of the paper and the quality of the printer's ink. If there is any danger, benzine should not be used, as the whole sheet may be cleared of grease marks almost equally well by covering it with a layer of chalk, placing a piece of blotting paper on the top of it, and pressing with a hot iron. Each leaf will, if necessary, have to be treated in the same way, and it may occasionally be found necessary to work on both sides of the paper. When this process is complete, the next step is to give each leaf a good general cleaning, and this may be done effectually by placing it in a leaden trough and pouring upon it a shallow surface of water. Two or three days of exposure to the rays of the sun will bleach the paper perfectly white, and all kinds of stains except fixed dyes will come out. The leaf is then dried (not in the sun or it will turn yellow), and is ready for the next process. It may happen that the sun is not available for this, or, indeed, any other purpose, and when such is the case, the surface dirt may be bleached off with a solution of chloride of lime in the proportion of one part to forty of water. The paper must be soaked in cold water before this mixture is poured on it, and both sides must be operated upon. This solution being essentially weak--if it were otherwise it would eat into the material--it is possible that it may be found unequal to the task of removing some of the more obstinate stains, which must therefore be touched with nitro-hydrochloric acid. Finally, the leaf must be well washed in a stream of running water, and allowed to dry naturally. Another method of removing surface stains sometimes used by restorers is to cover the paper with a thin layer of fine powdered salt. Lemon juice is then squeezed on the surface in sufficient quantities to dissolve the mineral, and the subject finally washed in boiling water. The chief objection to this process is the use of hot water, which, as may well be imagined, is apt to pulp the paper, or in some cases even to efface the printed text. Stains which cannot be removed by these processes are of several kinds. Lead pencil marks, for instance, will become fixed if the paper is damped, and they should therefore be helped out first of all with fine bread crumbs. Indian ink stains give way before a camel's hair brush and a cup of hot water, and all kinds of grease marks yield to benzine, turpentine, or ammonia.