Spirit of Nitre diſſolves the Metal almoſt inſtantaneouſly, Agua fortis is nearly as quick in its Operation, and Agua regia requires only a little Time: But of the others, ſome require long and tedious Proceſſes, and others act beſt, or perhaps only, by Vapour; and one of theſe Proceſſes ſhews, that where Mr. Boyle ſays, he knew a Menſtruum which by its Vapour would diſſolve a certain Metal, though it would ſcarce work on it at all in Subſtance; he is only talking of Copper and Vinegar. Sal Armoniac, it is to be alſo obſerved, affords us another Inſtance whence Nature may be ſupplied with a Menſtruum for giving a blue Solution of Copper; ſince, tho' the Sal Armoniac common among us now is factitious, there is no Queſtion but that there is, and ever has been, a true native Sal Armoniac; and there needs no more than Copper diſſolved in Water impregnated with it, to give the different Blues of all the deepeſt Sapphires in the World; it being moſt eaſy to procure a Solution of Copper of any Degree of Blue, only from a Solution of this Salt in Water, digeſted for a few Days on Filings of that Metal.
Nature therefore is not tied to one Menſtruum for the producing Blue from Copper; and that but a very ſcarce and uncertain one: Since it is evident, that the Bodies neceſſary to give it are many; and thoſe, many of them, common and every where abundant. That the common and univerſal mineral Acid, ſo abundant every where in all the Kinds of Pyrites,
the
