During the three months before my journey to Offenbach I practiced my art busily, and especially studied to attain thoroughness in one branch that was of importance to Herr Schulrath Steiner. I have spoken already of his idea for pictures for children. As soon as I had invented the new chemical printing, I thought of inking an etched copper plate with a composition of tallow, soap, lampblack, and oil varnish, making an impression, laying this on stone, and putting it through the press. The picture transferred itself to the stone as I had expected. Then I poured the water and gum solution over it and inked it with the ink roller. The design took the color well; and thus, if the stone was very clean in the beginning and the proof from the copper had been made very carefully indeed, I could print several thousands of copies which resembled the original so closely that only a slightly greater degree of sharpness, clearness, and strength gave the copper etching an advantage over the stone impressions. At last I succeeded in perfecting the process so that actually my best impressions from the stone were better than those that had been made with less care from the original copper plate. The main requisite in this process was that the ink be firm enough not to spread in printing, and still so greasy and tender that the very finest lines would come out. The copper plate had to be washed with extraordinary care, for the least bit of grease that should off-set on the white paper would, of course, transfer itself to the stone and make that part take color. This latter circumstance was intensely difficult to overcome. It occurred to me to treat the copper plate chemically, like the stone, so that its surface would resist the ink. I succeeded, as, in future, I succeeded with other metals. The fundamental principle in each case remained the same. Only in the choice of materials for each metal was there a difference. I discovered soon that there are two kinds of preparations, one acid and one alkaline, for all solid bodies which have the property of taking and absorbing oil colors. The alkalines seemed to be best for use on copper plate, and I obtained such clean impressions that the stone did not take on even a vestige of ink in any spot except the design. At the same time I found that chemical printing does not limit itself to stone, but can be done on wood and metal, as well as on paper, as stated already. Yes, though apparently it is incredible--even fats, such as wax, shellac, resin, etc., can acquire the attribute, under certain circumstances, of resisting color, and, therefore, are available for chemical printing. This fact gave me hopes of discovering a sort of artificial stone some day, which might be less costly, less massive, and less fragile; and, as a matter of fact, I succeeded in inventing an artificial stone-paper in 1813, a stony mass that is smeared on paper or linen and looks somewhat like parchment.