Page:Proceedings of the Royal Society of London Vol 60.djvu/40

32 From this it will be evident, from the horizontal position (b) (of the curve No. I) that the mass solidifies as a whole at 635° C .; but there is a second break cin the curve at a temperature of 407° C .; and there is yet a third break at d, 247° C. These latter points evidently are connected with the solidifying points of lead and zinc, but it is probable that these metals are, in solidifying, associated with some gold.

The second curve, No. II, represents the cooling of the same mass of gold with 10 per cent, of silver added. It will be seen that the metal has still one main solidifying point at 645° C. The lower point (c) of the former curve is entirely absent, but there is an indication of the lead point at 206°. The results clearly indicate that silver is a solvent common to both zinc and lead, which are not, as in the previous case (Curve I) free to separate from each other. Such a mass should be fairly uniform in composition, and assays from different portions of it proved it to be so.

Curve N o. II. 32 Mr. E. Matthey. Cooling of alloy of Au,Cu,Zn,Pb,

The latter curve (II) seems to change its direction at 767°, which is above the main solidifying point of the mass, and it remains to be seen whether this is of any significance.

The inspection of the curves so obtained at once led me to infer that silver mast be a solvent for zinc and lead when these are present