made in the ſame Proportions: And the Spirit of Verdigreaſe may very naturally excel both, as it is the ſtrongeſt vegetable Acid that Art can any way produce; though it is truly no other than a Vinegar abſorbed by Copper, and afterwards driven from it again by the Force of Fire; little altered, except as rendered more pure. It is remarkable, that Copper will thus part with this Acid in its proper and natural Form; whereas no other Metal will; for Iron and Lead, the only other Metals that will admit this Acid, alter it in the Mixture from its original Nature; for it can never be produced from them again in its natural State, but is in both Caſes quite a different Thing: When ſeparated from Lead, it appears in Form of an oily fat Liquor; and from Iron, little other than inſipid Water. The Spirit of Verdigreaſe is, however, the ſtrongeft of all vegetable Acids; and accordingly, extracts from Copper the Colour neareſt approaching to that of the Solutions of that Metal in ſome of the ſtrongeft mineral Acids.
Of the fixed Alkalies, Salt of Wormwood, Potaſhes, and Oil of Tartar per deliquium, all afford Solutions of Copper of a glorious, deep, celeſtial Blue, and no way diſtinguiſhable from one another, if the Solutions are made in exact Proportions. An Ærugo, of a greeniſh Colour, is indeed producible on Copper by theſe Menſtruums; and a ſmall Quantity of a ſimilar Subſtance is ſometimes found ſwimming on the Surface of theſe very Solutions: But this
