In order to ascertain the effect exerted by these two metals—lead and zinc—in conjunction with gold, I prepared an alloy of 700 parts pure gold and 300 parts pure lead, and after mixing and casting into an open mould I cast the melted alloy into a spherical mould 2 in. in diameter, made of cast iron. Determinations made from different parts, after cutting the sphere into two halves, gave the following results, the assays being made in triplicate upon each portion of metal removed.
(The weight of this sphere was a little over 2 kilograms.)
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Fig. 1.
The result shows a decided tendency of the gold liquate to the centre of the mass.
In the next experiment gold was alloyed with lead and zinc in the following proportions:—
G old............. 75 parts. L ead............. 15 „ Zinc ............. 10 „
adding the zinc when the alloy of the first two metals wras thoroughly fluid, and after casting this into an open mould, the alloy was remelted and cast into the 2-in. spherical mould before mentioned. This alloy was extremely hard and very brittle. Portions removed from the different parts of the sphere, after cutting it across, gave the following results :—
