1872.] Gold Coinage. 231 
It is well to allude to a difficulty incidental to coining, 
arising from the occasional brittleness of the gold alloy, which 
is generally due to the presence of minute quantities of lead, 
antimony, arsenic, or bismuth. Occasionally the use of 
impure copper to alloy the gold introduced these other 
metals, so very great care is taken in the selection of pure 
samples of copper. Imperfect annealing will sometimes 
make the gold brittle. The brittleness, however, is more 
frequently due to the admixture of baser metals. There is 
a remedy, however, for the evil, which is found to be the 
most simple and efficacious. It consists in sending a stream 
of chlorine gas through the molten alloy; the gas rapidly 
acts upon the baser metals, combines with them, and the 
chlorides are then driven off as vapour. In order to test the 
process, an experiment was made on gold made brittle by 
the addition of 0°05 per cent antimony and 0'05 per cent of 
arsenic, making a total base alloy of o'r per cent, while 0°05 
per cent of either metal would have produced very brittle 
gold. By passing a stream of chlorine through this gold, for 
33 to 4 minutes, it was converted into gold of excellent quality. 
Formerly, when bars of gold were found to be unfit for 
coinage, the impure metal was returned by the Mint to the 
importer, and the original melters, who were held respon- 
sible, not unnaturally objected to bear the loss. Now, in 
consequence of the successful result of the above-mentioned 
experiments, the Mint no longer rejects bars which during 
the process of coining are proved to be brittle: thus all 
vexatious disputes have been avoided. 
Of late years there have beem many important changes in 
the establishment of the Mint: of these probably the most 
important was that effected in 1848, namely, the abolition 
of the contract system, by which for many centuries the 
Mint had been worked. The old ‘‘ Masters of the Mint” 
were Contractors under the Crown, and their operations 
were controlled by officers, the principal of whom were the 
Warden and Controller, and the Assay Master, each exer- 
cising independent functions, the Assay Master being 
responsible to the Crown and to the people for the ‘‘ standard 
fineness” of the coin. 
After the abolition of the office of the “‘ Moneyers,” emi- 
nent scientific men have held the office of Master of the 
Mint. Now the office devolves upon the Chancellor of the 
Exchequer, and the appointment of an officer with the title 
Chemist of the Mint proves that the scientific requirements 
of the Department have been duly provided for ; indeed, the 
Reports which lately have been presented to Parliament, 
