Page:Theophrastus - History of Stones - Hill (1774).djvu/355

 is not purely the genuine Effect of the Mentruums, but a Change wrought in the Solutions made by them, by Particles of adventitious Salts floating in the Air; and mixing with a mall Quantity of them. Thee Changes of Colour in the Solutions of Copper from an Admixture of Salts of a different Kind, tho' but in mall Quantities, we hall ee hereafter in this Letter are very natural and eaily producible Effects; and we need not wonder at a mall Quantity of an Ærugo of this Kind floating on the Surface of the Mentruum, or affixed to a Plate of Copper, wetted with it, and expoed to the Air, tho' the true Solution of Copper in the Mentruum is blue; when we confider, that a Solution of the blue Vitriol in a Water impregnated with Sal Armoniac is green, notwithtanding that a imple Solution of Copper in that Salt is blue; (fuch is the endles Variety reulting from Mixtures of Salts as Mentruums) and that the natural Ærugo produced on Copper by the Salts floating in the Air, is green.

It is not to be wondered at, that the Solutions of Copper in the fixed Alkalies produced from different vegetable Subtances, are no way different from one another, ince thee Bodies act in thee Solutions, not as the peculiar Salts of this or that Plant, but as a Body made, not by any Operation of Nature, but by the Effect of Fire; which has trongly united the eential Salt, the Earth, and ome mall Portion of the Oil of the Vegetable they have been