Old books could be republished in this manner easily and without great cost. New ones also. I needed only to invent a fatty ink, similar to the printing-ink and drying thoroughly, and I could use every sheet of printed paper instead of type. I invented this ink soon. Resin, finely pulverized litharge of silver, lampblack, thick oil varnish, and potash properly diluted with water gave me a good ink for the purpose. The only obstacle that prevented me from using this process at once on a large scale was the fragility of the paper, which tore into pieces under the slightest carelessness in handling. The natural and simple thought that was bound to come to me under the circumstances was this, Could not a stronger material, perhaps the stone plate itself, be so prepared that it would take ink or color only on the parts covered with fatty ink, while the wet parts of the stone resisted it? I feared that the stone might not absorb the grease sufficiently, and this really is the case with many stones, such as slate, pebble, grindstone, glass, porcelain, etc.; but experiments showed that exactly the opposite is true in the case of the Solenhofer limestone. This stone has a great affinity for fat, which often is absorbed so deeply that in many cases even extensive grinding will not remove it. I took a cleanly polished stone, inscribed it with a piece of soap, poured thin gum solution over it and passed over all with a sponge dipped in oil color. All the places marked with the fat became black at once, the rest remained white. I could make as many impressions as I pleased; simply wetting the stone after each impression and treating it again with the sponge produced the same result each time. The impressions became somewhat pale, because the color on the sponge was too thin; but I obtained perfectly black and handsome impressions as soon as I used an ink roller of leather stuffed with horse-hair.