Before the Royal Academy of Sciences, and also before the Polytechnical Society of Bavaria, I demonstrated that chemical printing could be utilized with advantage on metal plates; but that still more useful was a composition of artificial stone which could be painted on metal, wood, stone, and even on plain paper or linen, and used in all processes exactly like the natural Solenhofen stone. The countless experiments that I have made in the past four years with this substitute (or, as some call it, stone-paper), in order to prove its usefulness under all circumstances, have filled me with the absolute conviction that it replaces the natural stone completely without having the many faults that in the nature of the case are inseparable from the use of the latter. In many respects it is far superior. The fragility of the Solenhofen stone requires the use of thick slabs for printing. If the impression is to be letter-sheet size, the stone must be at least one and one half inches thick if it is not to crack under pressure. If the stone is to be used for more than one job, the thickness must be two to three inches. To be sure, it can be ground and used over again some hundreds of times, a valuable consideration in view of the capital invested in a stone. But such a stone weighs from sixty to eighty pounds, sometimes more, and occupies considerable space. Add the investment necessary for laying in any great number of stones, and it becomes a difficult matter financially to undertake work that requires that the stones be held for a number of years, to be used for new impressions according to the sales of the work. Therefore it is necessary, generally, to print a maximum quantity at once, so that the stones may be ground and used for new work. If the stones are of thickness correctly proportioned to their area, the danger of cracking under the press is fairly remote; still, it does happen occasionally that a stone incurs damage through clumsiness of workmen. It can occur also through careless warming, or through sharp frost. In such cases even a strong stone will crack, especially if the workmen apply undue pressure. Besides, the necessary stones are not to be found in all places, so that the cost of transportation prevents the establishment of lithographic shops in many regions.