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before the copper melts: if the copper be first melted byitself, and the zinc heated and plunged into it, a strongcommotion ensues, though the dissipation is much lei'sconsiderable than in the other cafe, the zinc being quicklyimbibed by the melted copper and in some measureprotected and retained by it: if the copper and zinc bebrought separately into fusion, and one poured into theother, an explosion happens, and great part of the mixture,in my experiment above two thirds of it, is thrown aboutin drops, to the great danger of the bye-stander. Theunion appeared to succeed best, and with least loss of thezinc, when fluxes, containing inflammable matter, wereadded : I have generally used a mixture of black fluxand borax; to which may be substituted a cheaper compo-sition of twelve parts of green glass in fine powder, sixparts of potash, two of borax, and one of powdered char-coal. The flux is first to be brought into fusion in thecrucible, and the copper and zinc dropt into it: assoon asthese appear perfectly melted, they are to be well stirredtogether with an iron rod, and expeditioufly poured out.The fame flux serves repeatedly for the melting of severalfiesta quantities of the metal.

There are many receipts for making a gold colouredmetal, from verdegris a preparation of copper, and tutty apreparation or ore of zinc : the difference, above takennotice of, in the effect of zinc itself and of its common oreupon copper, induced me to try, whether, in this form ofcombination also, some useful variation might not happen.One of the best of these receipts seems to be that amongHook’s papers published by Derbam; in which eightparts of distilled verdegris (that is, verdegris purified bysolution in distilled vinegar and crystallization) and fourparts of Alexandrian tutty, with two of nitre and one ofborax, are directed to be mixed with oil to the consistence

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