1062 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[June 29, 1872, 
research, and promised to further increase his donation 
by ten guineas for each ninety subscribed for the same 
purpose. 
Mr. H. Deacon then delivered his lecture “ On Deacon’s 
method of obtaining chlorine, as illustrating some prin¬ 
ciples of Chemical Dynamics.” The process consists in 
passing a heated mixture of air and hydrochloric acid 
over sulphate of copper or over pieces of pumice or brick 
saturated with the same. He finds that the action is 
essential^ a surface action, and that there is a certain 
comparatively small range of temperature between the 
critical limits of which the percentage of hydrochloric 
acid decomposed varies greatly. The velocity with which 
the mixed gases pass over the surface of the active 
material also causes considerable variation in the com¬ 
parative amount of chlorine produced. 
After a vote of thanks to the lecturer, the meeting ad¬ 
journed over the recess. 
iparlianwntarj ani fate fwtttogs. 
PAPERS PRESENTED TO PARLIAMENT. 
Second Annual Report op the Deputy-Master of 
the Mint. 
The Report of Mr C. W. Fremantle, Deputy-Master of 
the Mint, concerning the operations in that establish¬ 
ment during the year 1871 has just been issued. The 
amount of gold coinage executed was far above the 
yearly average, which is about 5,000,000. But so ex¬ 
traordinary was the demand for gold coin which charac¬ 
terized last year that £9,798,735 was struck during 
that time, of which no less than £5,748,200 in sovereigns 
and £140,000 in half-sovereigns were coined and de¬ 
livered between the 25th of September and the 20th of 
December. 
The coins struck during the year were of four metals,— 
gold, silver, bronze and nickel, the last being pence and 
halfpence for use in Jamaica. The total number of pieces 
was 30,022,404, and their value, real or nominal, 
£10,580,061 11s. 5d. Of British coins there were sove¬ 
reigns and half-sovereigns in gold, florins, shillings, six¬ 
pences and threepences in silver; and pence and half¬ 
pence in bronze. Besides these there were fourpences, 
twopences and pence in silver, sufficient for “ Maunday 
money only.” It will not be out of place here to remark 
that the issue of crowns and half-crowns has been sus¬ 
pended since 1851, and that of groats or fourpenny-pieces 
since 1856. 
With reference to the first two of these coins a point 
is under consideration that marks the progress that has 
been made during late years in metallurgy. As is well- 
known, silver when extracted from its ores usually con¬ 
tains a small quantity of gold; but the process of re¬ 
fining as practised when the coins in question were 
struck was too expensive to admit of the extraction at a 
profit of the small quantity contained in them. At the 
present day, however, improvements in refining render 
it possible to extract with profit any quantity of gold ex¬ 
ceeding two grains in the pound troy of silver. Samples 
examined in the Mint prove that the half-crowns now in 
process of withdrawal contain an average of 4-07 grains 
in the pound, and when therefore any considerable quan¬ 
tity of these coins has accumulated in the Mint, it will 
probably be advisable to recommend that the gold should 
be extracted from them before they are re-coined. So 
long ago as 1831 this- subject was alluded to before a 
Parliamentary Committee by Mr. Mathison, the officer 
then in charge of the refinery at the Mint, and an 
opinion was expressed by him that the extraction of gold 
from the worn silver coin melted during the year would 
have been attended with an actual profit of £1412 to the 
public. 
The work in the melting-house is frequently pro- 
lon. ed by the steps which must, in many cases, be taken 1 
for recovering, before the daily account can be balanced, 
the portions of metal which may have remained in the- 
crucibles, or have been unavoidably spilt during the 
crack of the bars. {In the uncertainty which at present 
prevails as to the removal of the Mint to a new site, it 
has not been considered advisable to take steps for re¬ 
placing the melting furnaces now in use by those in 
which gas would be used as fuel; but sketches have been 
made by the chemist of the Mint of gas furnaces actually 
in use elsewhere, and the consideration of the question 
will be resumed whenever the opportunity may arise. 
In a memorandum by Mr. Hill, the Superintendent 
of the Operative Department, he states that the benefits 
derived from the introduction of plumbago crucibles for 
silver melting have been most marked, and he adds that 
they are not only better and cleaner, but also considerably 
cheaper than the iron pots formerly in use, and that the 
out-turn of each day’s work is far more satisfactory. 
The old crucibles are ground up in the same manner as 
those that have been used for gold-melting, and the- 
“ sweep ” is washed so as to obtain as much silver from 
it as possible, and is afterwards dried and sold. 
With regard to this “ sweep,” it may be stated that- 
hitherto it has been the practice to grind the crucibles,, 
ashes, etc., and to selljby tender such portions as pass 
through a sieve of forty meshes to the inch. With a> 
view to ascertain whether it was desirable to continue** 
the above-mentioned practice, or to undertake as an 
operation of the Mint the extraction of the precious* 
metals from the “ sweep,” Mr. Roberts, the chemist of 
the Mint, made a series of assays, but arrived at the- 
conclusion that comparatively small quantity resulting 
from a coinage of average amount could not be treated! 
with profit to the department. 
The actual deficiency of metal at the close of the 
gold coinage in June last was found to be 402,728 
ounces, the value of which in money was £1568 2s. 5d. f 
or £241 per million. The greater part of this deficient, 
metal having been recovered by the sale of the “ sweep ’” 
for £1240 13s. 4 d., the actual loss of the Mint on the* 
coinage was proved to be £327 9s. 1 d., or £50 per mil¬ 
lion. In this waste on the coinage of gold is included 
the loss attending the reception of light gold for re¬ 
coinage. This loss is due to two causes: (1) that a 
certain amount of dirt always adheres to the surface of 
the coins, the weight of which disappears in melting, 
and (2) that although received as standard gold, the 
light coins at present in circulation are found to be in 
reality below the exact standard of fineness, and to 
require the admixture of a certain proportion of fine 
gold before they can be again converted into coin. 
The method which has been recently introduced of 
toughening brittle gold by means of a current of chlorine 
gas is reported upon very favourably. Brittleness in 
gold is usually due to the presence of minute traces of 
foreign metals, and these metallic impurities are elimi¬ 
nated as chlorides by the passage of chlorine gas 
through the molten metal. The amount of gold set 
aside as unfit for working during the coinage of 
£6,500,000, which was completed in July, 1871,- 
amounted to 40,000 ounces. In the melting of gold, as 
ordinarily practised in the Mint, crucibles of graphite- 
are employed, but such crucibles are not well adapted, 
for use in the treatment of gold by chlorine gas, as the* 
gases evolved from them exercise a reducing action 
upon the chlorides. It therefore has been fouud advis¬ 
able to substitute crucibles of fire-clay for those of 
graphite. 
About 1100 ounces of gold are melted in each cru¬ 
cible, and the chlorine gas is pasaed through each in 
succession, the time during which the metal is exposed 
to the gas varying from five to seven minutes. The 
gold is found to be perfectly tough, and is re-assayed 
and again melted with the amount of copper required 
to form standard gold. 
