passim) οβρνζα is employed to designate the legal gold currency of the times, much in the same way as the word "sterling" at present.
This
test or assay consisted merely in making the gold, whose quality was to
be ascertained, red-hot in the fire, when, if the colour remained
unchanged, its freedom from all alloy was established. For with the
least admixture of copper, its colour was thus destroyed : our
sovereign, though of such high quality, treated thus, becoming coated
with a reddish-brown oxide of the baser metal. Some suppose this
red-heating gave the name to the test : a derivation perhaps supported
by Pliny's expressions : " Auri expe-rimentum ignis est ut simili
colore rubeat ignescatque, et ipsum obrussam vocant :
primum autem bonitatis argumentum quam difficillime accendi." The last
word, like " ignescere," signifies melting ; for, fusing at so high a
temperature as fine gold requires, a lambent flame plays upon the
surface of the liquified metal. To this test Martial alludes, where,
praising the fine quality of his golden phiala, he says (viii. 51),
"nee odit Exploratoire lurida massa focos."
For
this reason, " gold tried in the fire " is synonymous with " pure ;"
and the Byzantines called their aurei (even after they had lost all
claim to the title) înrépirvpoi, " superior to the fire;" out
of which word the Latins made the unrecognisable "perperi" their common
name for the bezants. This same primitive test was preserved in Akbar's
mint : " The skilful can discover from the colour with what the
superficial part is alloyed, and by the file and punch is learnt the
quality of the inside. They also try it by heating it in. the fire,
when, upon throwing it into water, blackness denotes lead ; redness,
copper ; a whitish-
