100.  Lithographic printing.  This is another mode of producing copies in almost unlimited number.  The original which supplies the copies is a drawing made on a stone of a slightly porous nature, the ink employed for tracing it is made of such greasy materials that when water is poured over the stone it shall not wet the lines of the drawing.  When a roller covered with printing ink, which is of an oily nature, is passed over the stone previously wetted, the water prevents this ink from adhering to the uncovered portions; whilst the ink used in the drawing is of such a nature that the printing ink adheres to it.  In this state, if a sheet of paper be placed upon the stone, and then passed under a press, the printing ink will be transferred to the paper, leaving the ink used in the drawing still adhering to the stone.

101.  There is one application of lithographic printing which does not appear to have received sufficient attention, and perhaps further experiments are necessary to bring it to perfection.  It is the reprinting of works which have just arrived from other countries.  A few years ago one of the Paris newspapers was reprinted at Brussels as soon as it arrived by means of lithography.  Whilst the ink is yet fresh, this may easily be accomplished:  it is only necessary to place one copy of the newspaper on a lithographic stone; and by means of great pressure applied to it in a rolling press, a sufficient quantity of the printing ink will be transferred to the stone.  By similar means, the other side of the newspaper may be copied on another stone, and these stones will then furnish impressions in the usual way.  If printing from stone could be reduced to the same price per thousand as that from moveable types, this process might be adopted with great advantage for the supply of works for the use of distant countries possessing the same language.  For a single copy might be printed off with transfer ink, and thus an English work, for example, might be published in America from stone, whilst the original, printed from moveable types, made its appearance on the same day in England.

102.  It is much to be wished that such a method were applicable to the reprinting of facsimiles of old and scarce books.  This, however, would require the sacrifice of two copies, since a leaf must be destroyed for each page.  Such a method of reproducing a small impression of an old work, is peculiarly applicable to mathematical tables, the setting up of which in type is always expensive and liable to error, but how long ink will continue to be transferable to stone, from paper on which it has been printed, must be determined by experiment.  The destruction of the greasy or oily portion of the ink in the character of old books, seems to present the greatest impediment; if one constituent only of the ink were removed by time, it might perhaps be hoped, that chemical means would ultimately be discovered for restoring it:  but if this be unsuccessful, an attempt might be made to discover some substance having a strong affinity for the carbon of the ink which remains on the paper, and very little for the paper itself.(2*)