Under the most favourable conditions there is a slight loss of gold and silver in the fusion, the scorification and the cupellation, both by absorption in the slag and by actual volatilization and absorption in the cupel.
The concentration of the button of lead may be effected either by scorification or by fusion in a crucible.
The scorificationassay is performed in a scorifier, which is a shallow open-mouthed dish about 2-1/2 inches across, with a very thick bottom to enable it to withstand the corrosive action of the slag.
As a general rule, it may be stated that when a scorification is unsatisfactory, what is wanted is more heat, more lead, or more borax.
Continue thescorification until a film, green when cold, floating on the surface of the button shows that the nickel is beginning to oxidise.
In some cases this preliminary scorification is advantageous or even necessary: this may be because the lead is hard and impure, or it may be that a very small button of gold is expected.
If the scorification has been unsatisfactory, the quantity of silver obtained from the slag will be by no means inconsiderable.
If the button of metal weighs more than 30 grams, its size is reduced by another scorification in the same scorifier, which should have been replaced in the muffle immediately after the contents had been poured out.
The process ofscorification is as follows:--A scorifier (fig.
If the slag forms properly, but shows unfused or only half-fused lumps, even when the scorification has proceeded for some time, add more borax, and stir with an iron rod.
If these larger cupels are not at hand the larger buttons will have to be reduced in size by a scorification before cupelling.
The salts facilitate the fusion and scorification of the unmetallic matters, and therewith form a slag, which being the lightest rises to the surface.
To separate Silver from its Ore, by means of Scorification with Lead.
When Sulphur predominates, the scorification proceeds more slowly, and doth not always succeed; because that mineral combined with Lead lessens its fusibility, and retards its vitrification.
To separate Silver from its Ore, by means of Scorification with Lead 238 2.
The Lead added on this occasion is intended to facilitate and expedite the scorification of the metallic substances combined with the Copper.
The difference between these two operations consists wholly in the substances made use of to procure the scorification of the imperfect metals, or semi-metals, that may be combined with the Silver.
Silver may be separated from its ore, and at the same time refined, by the single operation of the cupel, without any previous scorification with Lead.
It is with a view to save as much of it as possible that we order it to be covered with charcoal-dust as soon as the scorification is finished.
