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some stones reputed to be natural that had most lively Pictures, not only upon them, but passing thorow their whole substance, and thereupon finding an Artist, skilful to perform such rare workmanship, did not only pronounce such stones to be artificial, but when that Artist was unwilling to communicate unto him his Secret, did joyn his study and endeavors with those of one Albertus Gunter a Saxon, to find it out themselves: wherein having succeeded, it seems, they made the Experiments which this Industrious and communicative Jesuit delivers in this manner:
The Colours, saith he, are thus prepared; I take of Aqua fortis and Aqua Regis, two ounces ana; of sal Armoniack, one ounce; of the best Spirit of Wine, two drachms; as much Gold as can be had for nine Julio's (a Julio being about six pence English) of pure Silver, two drachmes. These things being provided, let the Silver, when calcined, be put into a Vial; and having powred upon it the two drachmes of Aqua fortis, let it evaporate, and you shall have a Water yielding first a blew Colour, and afterwards a black. Likewise put the Gold, when calcin'd, into a Vial, and having powred the Aqua Regis upon it, set it by to evaporate: then put the Spirit of Wine upon the sal Armoniack, leaving it also till it be evaporated; and you will have a Golden coloured Water, which will afford you divers Colours. And, after this manner, you may extract many Tinctures of Colours out of other Mettals. This done, you may, by the means of these two Waters, paint what Picture you please upon white Marble, of the softer kind, renewing the Figure every day for several days with some fresh superadded Liquor, and you shall find in time, that the Picture hath penetrated the whole solidity of the Stone, so that cutting it into as many parts as you will, it will always represent unto you the same Figure on both sides.
So far be, which how far it answers expectation, is referred to the Tryal of Ingenious Artists. In the mean time there are not wanting Experienced Men that scruple the Effect, but
