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for the brittlenese, which, gold, after fusion, is frequentlyfound to have contracted, and which has commonly beenascribed to other causes.' I have already taken notice,(page 69) that the general opinion among the chemicalwriters, of gold being made brittle by a piece of charcoalfalling, on. it in fusion, appeared to be a mistake, and I havesince found the seme observation made by M*. Scheffer,in an excellent paper on the parting of metals printed inthe Swedish transactions: he fays that in the royal mintof Stockholm, the gold is always covered with charcoal in,melting, and yet retains the full malleability which it hadbefore.. ,

Page 82. Fusibility of mixtures of gold and copper.

It has been affirmed, that though mixtures of gold andcopper melt easier than gold itself, insomuch as to serveas a solder for it; yet this does not proceed from any in-crease of fusibility occasioned by the mixture of the twometals with one another, but merely from copper beingmore fusible than gold, so that the more copper the mix-ture contains, the easier it ought to melt.. Admittinghowever that copper does melt easier than gold, whichby no means appears to be the case, an increase of fusibi-lity would still follow; for a mixture of gold and copper isa solder for fine copper as well as for fine gold.

Page 89. Calcination, cfr. of tin. with gold.

The experiment in which a mixture of gold and tin,calcined to an affi grey colour, is said to have melted with,ease into a yellow glass with a regulus at the bottom, Ihave now tried, but without observing any appearance ofvitrification — 1200 assay weights of fine gold, and 1800.

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