A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c18.s3.2

v1.c18.s3.2

If it were possible for our goldsmiths to work with pure gold, the appearance of the material would suffer very little by the various processes of heating, hammering, &c., and a mere mechanical rubbing would throw off the superficial dirt and be sufficient to expose the natural yellow surface of the unalloyed metal. This property of pure gold is due to the fact that no oxides of gold are formed at temperatures to which the metal is exposed during the operations of the goldsmith. Indeed it is well-known that gold does not unite with oxygen at any temperature.