Verdigris is difficult to manipulate because it smuts the stone easily and does not tolerate many mixtures. Schweinfurther green, one of the new colors, is much better in all respects, but not dark enough. Mixtures of yellow lake with indigo or mineral blue are not very durable. Golden yellow ochre with mineral blue or indigo does not produce a pretty green, and King's yellow mixed with blue is handsome but not durable. Neapolitan yellow and the newer chrome yellow with blue produce a green that is not dark enough. I have obtained the handsomest and darkest green by printing the design blue first and then printing over it a yellow plate, so that the yellow lay over the blue. By using Berlin blue and fine ochre a fairly handsome color is produced. On account of its loss of color in water, ochre cannot be used unless Venetian turpentine is first mixed with the varnish. A handsome and at the same time dark yellow is equally hard to obtain. Till a good color is invented, we must content ourselves with ochre, Terra de Sienna, Neapolitan yellow, mineral yellow or chrome. This printing with various colors is a process for which the stone is superior; and it is susceptible of such perfection that in future true paintings will be produced by its means. My experience convinces me of this. IX GOLD AND SILVER PRINTING This process is useful for decoration. Those parts of the design that are to appear in gold or silver are drawn with chemical ink on a stone prepared for pen work. After the drawing is dry, it is etched and prepared in the usual way. The printing is done with a silver gray color of firm varnish, fine crayon and a very little lampblack. The paper must be entirely dry and very smooth. Soon after the impression has been made, the printed parts are covered with silver or gold leaf such as is used by gilders. It is pressed on slightly with cotton, that it may adhere, and then a sheet of paper is laid over it. Then the second impression is made, treated the same way, and so on. No more impressions must be made than one can cover with silver or gold in two hours. If the ink is on the paper too long, it will draw in and not take the metal well. After gilding or silvering, the sheets must lie for some hours or till the next day, that the ink may take perfect hold of the paper, so that, in the succeeding pressing, it will not penetrate the metal and make it look sooty. The pressing is done by laying six or eight impressions on a clean stone under the press and passing them through as for printing, with the proper tension. This tension must be adjusted according to the firmness of the printing-color; therefore it is best to make test with one sheet. Then, if the metal does not adhere sufficiently, the pressure can be increased.