[ 165 ]

Mr. Eller, in the memoirs of the Berlin academy forthe year 1747, describes a process somewhat differentfrom the foregoing ; which has been kept a secret in afew hands ; and from which, he fays. Saxony has forseveral years reaped considerable profits, by the separationof gold from gilt laces.

The metal being granulated, a part of the grainsis mixed with half their weight of litharge and aneighth of fandiver : this is called the precipitating mix-ture. The rest are mingled as above with powdered sul-phur, and exposed to a gradual fire till they are broughtinto fusion, which is known to be perfect, when the sur-face, on lifting up the cover of the crucible, appearscoloured, chiefly with red and yellow, and the colourscome and go, as if something attracted them. To everythirty-two ounces of the sulphurated metal, one ounce ofthe precipitating mixture is added, at three different times,at intervals of at least five or six minutes ; after which,the crucible is covered again, and the fusion continuedseven minutes. Part of the matter being now laded out*the rest is poured off, till a metallic mass strews itself atthe bottom : this is easily distinguishable, by its brightfiery aspect, from the sulphurated mixt, which is of aleaden brown colour.

The silver poured off, still containing a little gold, istreated in the fame manner a second and a third time, ex-cept that in the third another precipitant must be used *for that employed in the two first, being partly composedof silver not freed from its gold, would add to the sulphu-rated silver, now almost entirely purified from gold, moregold. The precipitant is now a mixture of equal parts ofpure copper and lead, melted together and reduced intograins. If aqua fcrtis should still discover a little gold inthe silver, which never happens unless the silver contained

a large