The next and last, alludes to the amalgam, which appears to have been for many centuries a favourite method of applying gold to parchment and other surfaces. "Melt some lead, and frequently immerse it in cold water. Melt gold, and pour that into the same water, and it will become brittle. Then rub the gold filings carefully with quicksilver, and purge it carefully while it is liquid. Before you write, dip the pen in liquid alum, which is best purified by salt and vinegar." In these instructions the student may distinctly recognize the processes adopted in the production of those gilt texts on stained vellum grounds which were so highly prized in the Carlovingian age. In the writings of an ecclesiastic, probably nearly contemporary with the Norman conquest, the monk Rugerus, or "Theophilus," we arrive at a really perfect picture[107] of the arts of the 11th century. The first of the three books into which his "Schedule of different Arts" is divided, is dedicated entirely to painting. It contains forty chapters, of which thirty refer to the preparation and application of pigments generally, both for oil, tempera, and fresco painting, and ten to the various processes connected with illumination. Of these, the following are the most important:-- CHAPTER XXX. OF GRINDING GOLD FOR BOOKS, AND OF CASTING THE MILL. When you have traced out figures or letters in books, take pure gold and file it very finely in a clean cup or small basin, and wash it with a pencil in the shell of a tortoise, or a shell which is taken out of the water. Have then a mill with its pestle, both cast from metal of copper and tin mixed together, so that three parts may be of pure copper, and the fourth of pure tin, free from lead. With this composition the mill is cast in the form of a small mortar, and its pestle round about an iron in the form of a knot, so that the iron may protrude of the thickness of a finger, and in length a little more than half a foot, the third part of which iron is fixed in wood carefully turned, in length about one yard, and pierced very straightly; in the lower part of which, however, of the length of four fingers from the end, must be a revolving wheel, either of wood or of lead, and in the middle of the upper part is fixed a leather strap, by which it can be pulled, and, in revolving, be drawn back. Then this mill is placed in a hollow, upon a bench fitted for it, between two small wooden pillars firmly fixed into the same bench, upon which another piece of wood is to be inserted, which can be taken out and replaced, in the middle of which, at the lower part, is a hole in which the pestle of the mill will revolve. These things thus disposed, the gold, carefully cleansed, is put into the mill, a little water added, and the pestle placed, and the upper piece of wood fitted, the strap is drawn and is permitted to revolve, again pulled, and again it revolves, and this must