230 Gold Coinage. [April, 
similar properties. The button is reduced by rolling to a 
thin strip, which is annealed and bent into a loose coil or 
“‘cornet.” The cornet is placed in nitric acid of the specific 
gravity of 1°25, and the acid is maintained at incipient 
ebullition for fifteen minutes; the coil is then treated in a 
similar manner with nitric acid of the specific gravity of 1°4, 
the result being that the silver is removed by the action of 
the acid, and the gold remains in a spongy state. The 
sponge of the gold retains the original form of the coil, but 
it is necessary to impart a certain degree of coherence to 
the metal by annealing it at a dull red heat. A small quan- 
tity of silver is invariably retained with the gold. It is 
necessary therefore to make check assays on the pure gold, 
or on standards of known composition, upon which the 
accuracy of the result will in a great measure depend. The 
concluding process consists in weighing the gold cornet. 
The weights employed beara decimal relation to the original 
weight of the assay piece operated upon, and the amount of 
gold therefore present in the alloy is at once indicated with- 
out further calculation. 
Analysis of assay reports,* extracted from an official 
memorandum by the Chemist of the Mint, shows that coins 
taken from half a million of gold pieces, issued by the Mint 
in the year 1870, had the following composition :— 
; ; Per Mille of Gold. 
a per centol the coins’contained . . 32 2) Ord 
a0) PP oe 5 ote « « OOM 
25 5 ¥s a oS ue fe oe (Once 
29 . », were of exact standard 916°6 
14 s 5» Contained i . . “+ sonar, 
9 ns - Ae oe S| ee ORNS 
8 i ‘rf Pe es 6 «2 “, “OllOng 
2 AA 3 A toe Se HOES 
100 
Mean composition of the coins . | oe ae 
I,000,000 
That this result exhibits the attainment of a very high 
degree of accuracy will be evident when it is remembered 
that the allowance prescribed by law would have permitted 
a variation, above or below the exact standard, of two parts 
in the thousand. 
* Appendix to First Annual Report of the Deputy Master of the Mint (1870). 
