The art of gold tooling on leather appears to have been known in Eastern countries before it was known in the West. There are signs of it in Saracenic work of the early fifteenth century, but it cannot be quite certain whether much of this work was not simply painted with gold. If a blind line is carefully painted with gold shell and then burnished with a fine agate, a gilded line can be made that looks nearly as well as a properly gold tooled line. No doubt a considerable proportion of early gold tooling was done in this way, and some of it was not even burnished. Some early Venetian bindings show gold spaces gilded with gold leaf in a very effective way, and in the Bodleian some English panel stamps of the early sixteenth century are gilded all over. [Illustration: FIG. 100.--Italian gold tooled binding, 1514.] There is little doubt that gold tooling, done as it is now, was known to the Venetians towards the end of the fifteenth century. It is a curious art, and depends for its wonderful strength upon the fact that albumen hardens with heat. The method used is simple: a stamp is impressed in blind on the leather, and then the impression is painted over with glaire of egg--albumen. When the albumen is dry it is again painted over with palm oil or cocoa-nut oil, and on this a piece of gold leaf is laid. The stamp is now heated, and when it is of the proper temperature it is very carefully reimpressed in exactly the same place as at first. The heat of the stamp congeals the albumen under the gold, and the now gilded impression is likely enough to be the strongest part of the leather. I have often found old leather bindings badly worn away, but the gold tooled work and lettering still remaining in places. Thus, instead of being _impressed_, as it originally was, it is all in _relief_, because the albumen has soaked into the leather a little and then been hardened, so that instead of gilded hollows we find little mountains with golden tops. But to counterbalance this possible advantage, the albumen presents a weak point. On an old gold tooled binding it is not uncommon to find that a golden curve is partly gone; half of it perhaps shows no longer as a thin gold line, but only as a shallow trench, hollowed out of the leather. The meaning of this is that the albumen provides a nourishing meal for some small grub, which, once it gets the trail, will follow it, if not disturbed half over the book, and with wonderful accuracy will eat away gold, albumen, and a little leather, following curves, leaves, and letterings with close fidelity. This particular damage is most liable to occur in instances where books are laid down in show cases on cloth or velvet and not often moved. The soft groundwork allows the grub more freedom than if the book is standing up closely packed with others on a shelf. The small gilt roundels found on early Persian and Arabic bindings as well as on early Venetian work, were set with some sort of gesso under the gold.