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substances containing it; the one, as is staid, by Iiom-berg (for, though given as strom him by some late repu-table writers, I cannot find it among his papers in theFrench memoirs) the other by Vigani.

In Homberg’s method, the copper is to be amalgama-ted with pure quicksilver, the amalgam boiled in riverwater for two hours, the quicksilver distilled off in a re-tort, and again poured back and abstracted once or twice :the remaining copper, being now fused, is staid to appearof a beautiful gold colour, and to be more ductile thancommon copper, so as to be well fitted for the finermachines and utensils. The great difficulty of amalga-mating copper by the common methods seems to haveprevented this process from coming to a fair examination.This difficulty I have surmounted in different ways: oneof the easiest and most expeditious of which was, bydissolving the copper in aqua fortis, and, when themenstruum would take up no more, pouring the solutioninto an iron mortar, along with six times as much quick-silver as there was of copper, and some common salt,and then grinding them well together with an iron pestle :the dissolved copper is extricated from the acid by theiron, in a very subtile form, and falling in this state intothe quicksilver, is readily imbibed by it. This amalgamwas ground and washed with water till it became per-fectly bright, and the mercury was then distilled off:the remaining copper, melted in a crucible, had, as wasindeed expected, no degree of yellowness, and appearedexactly of the fame colour as at first. As no sensiblealteration was thus produced, a repetition of the trouble-some operation was judged unnecessary.

Vigani’s process carries with it strong marks either oferror or reserve; yet from the general character of theauthor, and the favourable reception he met with in this

F f 2 country.