At that time I could not guess that I was to invent a form of printing different even from this new and original form, a method which was to be based not on mechanical but purely chemical properties. Even this method, new in 1796, still was purely mechanical in its purpose, whereas the present printing method, which I began in 1799, may be called purely chemical. I had just ground a stone plate smooth in order to treat it with etching fluid and to pursue on it my practice in reverse writing, when my mother asked me to write a laundry list for her. The laundress was waiting, but we could find no paper. My own supply had been used up by pulling proofs. Even the writing-ink was dried up. Without bothering to look for writing materials, I wrote the list hastily on the clean stone, with my prepared stone ink of wax, soap, and lampblack, intending to copy it as soon as paper was supplied. As I was preparing afterward to wash the writing from the stone, I became curious to see what would happen with writing made thus of prepared ink, if the stone were now etched with aqua fortis. I thought that possibly the letters would be left in relief and admit of being inked and printed like book-types or wood-cuts. My experience in etching, which had showed me that the fluid acted in all directions, did not encourage me to hope that the writing would be left in much relief. But the work was coarse, and therefore not so likely to be under-cut as ordinary work, so I made the trial. I poured a mixture of one part aqua fortis and ten parts of water over the plate and let it stand two inches deep for about five minutes. Then I examined the result and found the writing about one tenth of a line or the thickness of a playing-card in relief. A few finer strokes had been injured slightly, but the others had hardly lost breadth noticeably and not at all in depth, so that I had good reason to hope that a well-written plate, particularly in type letter, would be susceptible of much better relief. Eagerly I began inking in. I used a fine leather ball, stuffed with horsehair, and inked it very gently with thick linseed oil varnish and lampblack. I patted the inscription many times with this ball. The letters all took the color well, but it also went into all spaces greater than half a line. That this was due to the over-great elasticity of the ball was clear to me. So I cleansed my plate with soap and water, made the leather tense, and used less color. Now I found color only in such spaces as were two or more lines apart. I saw that I could attain my purpose better with a dauber of stiffer material. I tried at once with a piece of glass from a broken mirror, and as this succeeded fairly well, I tried elastic metal plates. Finally I made an entirely satisfactory appliance out of a thin board, very smoothly planed and covered with a fine cloth.