Physical Properties of Gold

Gold is a metal of characteristic yellow colour. Its melting-point is given as 1035° C., 1037° C., 1059.3° C., 1061.7° C., 1062.4° C., 1063° C., 1063.9° C., 1064° C., 1071° C., and 1072° C. The most probable value is about 1063° C. Capua found that the presence of between 6 and 7 per cent, of silicon lowers the melting-point about 800° C. Its boiling-point was determined by Moissan with the aid of the electric furnace to be about 2530° C., being higher than that of copper and lime. Its density is given as 19.21, 19.2685, 19.28, 19.43, that for unpressed gold being 18.884. The approximate value may be taken as 19.3. The specific heat at low temperatures is given as 0.0297, as 0.0302 at 0° C., as 0.0380 at 18° C., and as 0.0324 and 0.0316 at 0° to 100° C. The latent heat of fusion per gram is 0.0163 Cal. The hardness on Auerbach's scale is 2.5 to 3. Gold is the most malleable of the metals, and can be beaten out to leaves 0.0001 mm. thick. One gram of the metal can be drawn out to a wire 166 metres in length. Thin layers deposited on glass by heating in vacuo are almost colourless in reflected light, but appear of a rose to violet colour by transmitted light. Neither hydrogen nor nitrogen is absorbed by gold, either in the solid or fused state. It is a good conductor of both heat and electricity.