in a few lines an experiment performed by order of Caligula for fabricating gold with sulphuret of arsenic (or orpiment). There was thus a whole special chemistry, now abandoned, which was conspicuous in the practices and pretensions of the alchemists. A patent has been obtained in our own times for an alloy of copper and antimony, containing six hundredths of the latter metal, which presents most of the apparent properties of gold and is worked in the same manner. Alchemic gold belonged to a family of similar alloys. Those who made it fancied besides that some agents played the part of ferments to multiply gold and silver. Before deceiving other people they deluded themselves. Sometimes the artisan was satisfied to use a cement or superficial action, painting the surface of silver in gold or the surface of copper in silver, without modifying the metals in their thickness. This is what goldsmiths still call giving color. They would even do no more than apply to the surface of the metal a gold-colored varnish, prepared with the bile of animals or with certain resins, as is still done. From these colorings the operator, led by a mystic analogy, passed to the idea of transmutation, in the false Democritus and in the Key to Painting. The author of the last work concluded, for example, with the words, "You will thus obtain excellent gold and fit for the test." The author added further "Hide this sacred secret, which should be delivered to no one nor to any prophet." The word prophet betrays the Egyptian origin of the recipe. It refers to the Egyptian priests, who, according to a passage in Clement of Alexandria on the Hermetic books that were borne with great pomp in the processions, were called prophets.
In further proof of the Greco-Egyptam origin of goldsmiths recipes contained in the Key to Painting is the existence m the Latin collection of ten recipes—some of the elaborate ones—which are phrased in precisely the same terms in the Greek papyrus in Leyden; the former text being translated from the latter even to the detail of certain technical expressions, which are still perpetuated in the goldsmiths' manuals of the present. This does not mean that the text transcribed in the Key to Painting was originally translated from the very papyrus that we possess, which was not found till the nineteenth century at Thebes, Egypt; but the coincidence of the text proves that there existed books of secret goldsmiths' recipes transmitted from hand to hand of the tradesmen, which continued through the middle ages, and of which the Key is an example. It was firmly believed m the time of Diocletian that the Egyptians had the secret of enriching themselves by making gold and silver; and in consequence of this belief after a revolt, the emperor ordered all their books burned. Nevertheless, as we have seen, the formulas did not disappear.
