TAA i.3.14.2

                                      (2)

period – Author’s Note.), although there is no certain

reference to it in the description of the objects.

The reddish-brown colour gives the test for iron,

silver and copper, and it is evidently due to

iron and copper in the gold that have oxidized. 

In some instances a red or purple colour proved

to be a staining of the gold by organic matter, since

it was not soluble either in acids or in organic solvents, 

but could readily be removed by heating. The

rose colour can be proved by chemical analysis 

not to be due to any colloidal modification of the

gold, nor to any sort of organic lacquer or varnish,

and the gold can be made red-hot without the

colour being removed or diminished, but in

some instances rather enhanced. The coloured 

film, however, is so extremely thin, being probably less

than one hundred-thousandth of one inch in thickness, 

that without more material than it is desirable to use,

chemical analysis becomes very difficult. A

trace of iron is the only metal found so far, and 

since it is well known that native gold is sometimes 

reddened by being coated with a translucent film

of oxide of iron, it is suggested that the colour in