The Liverpool Standard and General Commercial Advertiser.
Liverpool, Merseyside, England, 1836-12-20 00:00:00

LECTURE X.

On Saturday evening Mr. Hemming proceeded with his
valuable and interesting course.
Gold was abundantly found in ancient times, and as highly
valued as at the present day. We frequently find it alluded to
in the Scriptures; thus we read that Solomon received in one
year 6GG talents of gold, or 76,0001b5. weight, and that all his
drinking vessels, as wall as all the vessels of the house of the
forest of Lebanon, were of fine gold. None were of silver: it
was nothing accounted of in the days of Solomon. The great
beauty, lustre, malleability, and ductility of this metal, its un-
changeable nature, as well as its comparative scarceness, caused
it to be as much appreciated formerly as at present. As gold is
found in its native state, although mechanically united with
other substances, the art of reducing might have been very
easy, and, in all probability it was, incidentally discovered. In
modern times gold is chiefly found in South America, but there
is scarcely a metal which is more universally distributed over
the whole world, except iron and arsenic, but its quantity is so
small that it is rarely worth the trouble of separation. In the
sixteenth century it was found in the mines of Upper Hungary,
and worked with great success. It has been found also in
Cornwall and in Scotland. The largest quantity ever found in
the three kingdoms was discovered in the Wicklow mountains,
of the weight of 22 ounces. A mass of gold has been met with
in South America weighing 448 ounces, and another 528 ounces,
but the average quantity met with is from five to six ounces in
50001bs. weight of ore. A few years ago part of a mountain in
Paraguay fell down, and masses of gold, from 20 to &Abs. weight,
were found. The followers of Christopher Columbus found such
large quantities of gold, in such large masses, that they thought
they had found the Eldorado. A labouring man or a sailor
sometimes found as much in a day as was worth £2OO. Gold is
found in great abundance between the tropics. All regions
nevertheless contain it, and it is probable that mountains contain
considerable quantities of it, and that it is washed down into the
rivers by rain. We receive annually 4000 ounces of gold dust
from Africa, which is separated from the sand of the rivers
flowing through that country. Great quantities of gold are
found in the sand of the river Aranos, the collection of which
affords employment to 7000 families. The current of one of the
rivers in Brazil was turned fur the purpose of extracting the
gold from its sandy bottom. Many of the European rivers
contain particles of gold amongst their sands ; amongst these
are the Rhine, the Rhone, the Danube, the Tagus, the Elbe,
the Oder, and the Schwaritz. Gold seeking is a very bad trade
in Africa, and very indifferently rewards those engaged in it.
The mode of separating it from the river sand is extremely sim-
ple. The natives judge from the appearance and colour of the
-sand whether it is rich in gold. It is found in greatest abun-
dance in.rich ochreous sand containing iron, after heavy storms
of rain, by which it is brought down from the mountains by the
force of the torrent. When the particles of gold are separated
from the sand they are found perfectly smooth, as ifabraded by
the action of the sand and water. Now those who collect the
gold keep the sand containing it in perpetual agitation iu a
vessel beneath the surface of the water, by which means the gold
sinks to the bottom by its greater gravity. They continue this
process until they think a quantity of gold has accumulated at
the bottom of their vessel, when they pick out its minute. parti-
cles. k'pr commercial purposes this process is pursuer ll un a
larger scale, and mercury employed for the purpose of forming
an amalgam with the gold. The excess of mercury is then
strained off through leather ; and the amalgam being subjected
to a sufficient degree of heat, the mercury is driven off, and we
have a button of tolerably pure gold remaining. When gold is
in the state of ore, or combined with the baser metals, excepting.
silver, it must undergo the process of refining by the refiner's
hearth. The alloy which contains the gold is wrapped up in
sheet lead, and placed on the hearth of the furnace, and a very
intense fire is allowed to play upon it. First the lead will melt,
and, becoming an oxide, be converted into a vitreous state,
when the baser metals will combine with it, leaVing the gold in
the cupel in a pure state. The workman knows when this
takes place, by the surface of the metal appearing quiescent,
and of a greenish colour. When silver is alloyed with gold the
mode of separation is that described in the previous lecture.
That process is called planation. In modern times another
mode is resorted to. The alloy containing silver is rolled into
sheets, and placed in nitric acid. The nitric acid will dissolve
the silver but rot the gold. The mode of reducing it from ore
in the South Atnerican mines is, first to stamp it into a coarse
powder, in stamping mills. The powder is then placed upon au
inclined plane with ledges, covered with sheep skins, or some
other fibrous material. A stream of water is permitted to flow
upon this inclined plane, which carries away gradually the
lighter portions of the ore. The particles of gold and other
metals, being so much heavier than the matrix, are kept to-
gether by. the fibres of the sheep "skins; which have a remarkable
tenacity in keeping these particles of gold. The particles are
then beaten and washed out of the sheep skins, and they un-
dergo the process of amalgamation aad beating iu a cupel, as
previously described.
We may dissolve small portions of gold in liquid chlorine, but
nitro-muriatie acid composed of two parts muriatic to one part
of nitric acid will easily dissolve it in large quantities. All the
other common metals, except platinum, are dissolved in nitric
acid, threfore by this means we separate them from gold. The
gold of commerce is never pure; in order to obtain it Co we
must resort to this process, though, in the opinion of some che-
mists it cannot be procured chemically pure, unless it be fur-
ther separated from foreign substances by dissolution in sul-
phuric ether. We then have the heaviest known metal but one,
dissolved in the lightest known fluid but one. By evaporating
the ether we have perfectly pure gold. This etherial solution
of gold was formerly employed in medicine, and supposed to be
a panacea for all kinds of diseases, in fact it was considered
equal to Morrison's pills. But it is no wonder, because the
physician compelled the patient to furnish him with the gold to
dissolve, a little of which probably was returned to the patient
in the medicinal state. Our physicians, however, in these days
manage matters much better;—they never profess to cure any
patient by returning any portion of gold. We may gild steel
articles by means of this solution. In this way the eyes of la-
dies' needles are gilded. Lancets, pen-knives, swords, and
other bright steel instruments may, in this manner, be protected
from the weather.

Pure gold is too soft for our domestic purposes, and there-
tore it becomes necessary to alloy it with something to make it
hard. Copper is chiefly used for this purpose, especially at the
mint. In estimitirg the purity of gold the term carat is em-
ployed; every portion, of gold is supposed to be divided into
twenty-four parts, and. each of these is called a carat; if the
alloy contain eighteen parts gold and six alloy, it is called gold
oitgtatiawn rarats fino_ C urgold enin is ugnally twanty.two ca-
rats fine. Now in Great Britain every article of gold and silver
above a certain weig,ht.must be stamped, and in order to ascer-
tain whether it be of the required degree of fineness evesy arti-
cle sent to Goldsmiths' Hall undergoes the operation of assay-
ing. For this pnrpose minute portions of the article are de-
tached by means of a file, and the alloy is fused in a cupel, ac-
cording to the previously mentioned process, when the gold ob-
tained by this means free from the alloy •of copper is weighed
and contrasted with the previous weight of the alloy. When
gold is alloyed with silver the process of quartatiou must be re-
sorted to. In France the gold must be twenty carats fine, but
in England gold of eighteen carats fine is considered standard.
The French mode of assaying gold differs from that of the Eng-
lish. The manufacturer states the alloy. The article is then
rubbed upon a touchstone, and the mark very accurately no-
ticed. The workman then rubs a needle composed of similar
alloy upon the stone, and if the needle touch similarly to the
article being assayed, and leave a similarly tinted mark the
gold is considered standard. Such is the skill and dexterity
which these workmen possess by their continual practice that
they seldom err. The high duty paid at Goldsmiths' Hall on
the various articles assayed there has induced many persons to
commit singular frauds upon the public. A person . used to
come regularly to the hall to have a pair of light gold watch
cases assayed, until one day the assayer noticed a flaw in the
cases similar to one which he had made in a similar pair as-
sayed previously and stamped. This led to suspicion, and it
was found that the watch-case maker was in the habit of cutting
the hall mark out of the case, and soldering it into other gold
cases of inferior purity, The art of soldering gold is carried to
such a degree of perfection that few ladies can tell where their
wedding rings are soldered. The fraud was detected, and the
man transported.
The next metal we have to consider is silver. Like gold. this
metal has been found in all parts of tha world, but chiefly in
cold countries. The greatest quantities of it have been found
in the high lands, or mountains in Mexico and Peru, which are
considerably elevated above the level of the sea. The chief
sources of it in Europe have been the cold countries of Bohe-
mia, Sweden, Norway, and Transylvania. We.have no silver
mines in England, and yet with the exception of Hungary no
European kingdom has produced so much silver. It is found
in the galena or sulphuret of lead. The quantity, however,
is not always sufficient to render it worth extracting. We have
had such enormous quantities of silver found in early times in
this galena, that some geographical writers have awned that
silver mines formerly existed in England. It is said' that in the
reign of Edward I. a mine in Devonshire yielded .16001bs.
year, and that another in Derbyshire was Si rich in it that
671bs. per ton were extracted from the lead ore. Sir Hugh de
Middleton, of Cardigan, obtained an immense amount of silver
from his lead mines (between 60 and 80 oz. from the ton) with
the proceeds of which he was enabled to complete the
.stupen-
dous undertaking of bringing the new river from Herefordshire
to London, an enterprise which, though it ruined him, has
been the fortune of many.
The quantity of silver contained in the same specimen of ga-
lena often varies. The crown, formerly, could claim any mine in
the kingdom, provided it contained as much gold or silver as
was worth mobile separating- accordingly, an action was brought
by the crown in a court of justice, in 1690, against the pro-
prietois of several mines, but the proprietors proved that the
varying quantity of silver found in the ore would not repay the
working of the mines, and gained a verdict. This right of the
crown was given up in the reign of William and Mary; but, lo
the present day, the crown has a prior right in the silver
obtained in the kingdom at a rate above a market price of the
ore. Silver is refined in the same manner as gold, and can be
separated from lead by cupellation. Pure silver is the whitest
and most lustrous of metals. It is obtained in the greatest
quantity from the mines of Potosi, in Mexico. This mine was
discovered by accident : an individual named, Diego Huelpa,•
was hunting a llama on the mountain of Potosi, and, being in
danger, caught hold of a shrub, which, yielding to his grasp,
discovered to him a quantity of pure silver about its roots. He
replaced the shrub; but, as he could not work this mine alone,
he communicated his secret to a fellow workman. They
worked it by night, and removed large quantities of silver;
but, Huelpa's fellow-workman having revealed the secret in a
fit of drunkenness, the mines were seized by The Crown, and
became the royal property. From the commenceinent of the
working of this mine to the present century, the quantity
of silver obtained from these mines has exceeded three
hundred millions of pounds, and within a few years of its
discovery, although it existed in a barren mountain, a town
was built near it which contained 10(1,000 inhabitants. This
mine, it is said, is not by any means so productive as formerly.
Silver, like gold, is little liable to alteration. It, however,
combines very freely with the sulphur of the sulpburetted hy-
drogen, and tarnishes much more readily than gold. If it be
exposed to a violent heat it will not burn, but it will boil; and
if a gold vessel be held over the vapour of the boiling silver, it
will be coated with a film of silver. Nitric acid is the best
solvent for silver; but we may disiolve a minute portion of it
in boiling sulphuric acid. Nitric acid mixed with one-half its
weight of water will dissolve one-half its weight of silver.
When the excess of acid and water is evaporated and the salt
fused, it will communicate an indellible black to the skin, and
is employed in dyeing various substances black. Gold commu-
nicates an indelible purple stain to the skin. Now silver is
very extensively used in this state, in which it is chemically
called nitrate of silver, but commonly lunar caustic. It is ern,
pMoved as a caustic for the purpose of arresting the progress of
loc;l inflamation. it is employed in the preparation of eye
water, in the proportiou of one or two grains to an ounce of ,
water, in which state it is an invaluable lotion for weak eyes.
It is likewise taken in cases of epilepsy, but it has the
singular property of staining the whole s, of of a deep slate
colour, approaching to blackness, which nothing will remove.
This article is likewise employed in the preparation of indelible
-hi • is sold •
nitrate of silver,
i thickened with gum and coloured with Indian
marking ink. Now this marking ink, is at such an
enormous price, is nothing but a solution of
nk. It is not
considered sufficient by the druggist for his customer to buy
marking ink, but he must buy a bottle of preparation at the
same time. Now this preparation is merely a little pearlash
and wafer• coloured red. In order to write wit it this, time linen
the alkaline liquor. It is
or otl.ier material is to be dipped in

then to be dried and rubbed over with a smooth tool, to give ft
a smooth surface, and we then write upon it with a solution of
the nitrate of silver, prepared as previously stated. We have
also another use for nitrate of silver, iu a state of solution, and
it is supposed there is almost as much of this sold as °fare marking
ink, undertlifferent names, the most common of which is Tyrian
dye. Now this Tyrian dye, which is mostly used for. the purpose
of dyeing gentlemen's whiskers, is nothing inure than a solution
of nitrate of silver; and it unfortnoately happens that, many
gentlemen are not aware that it will communicate the .same
beautiful jet black colour to the skin. Many indescrible ac-
cideuts have arisen front this circumstance. Oire of these came
under Mr. Hemming's notice. A gentleman recently imported
from the sister isle, attended a hair-dresser, and when the
journeyman was perfurrniug his important office, enquired
of him whether he had not some substance which would dis-
charge the colour of his fiery-red whiskers. He replied that
he had, and procured it front his employer. His employer
asked whether lie knew how to apply it, and was answered in
the affirmative. This Mall was also a native of the sister isle.
A little time afterwards the hair-dresser observed that the hands
of his assistant were of a deep black, and upon enquiry, he ascer-
tained that the man had applied the dye with his hands to the
gentleman's whiskers. I a short time the gentleman himself
returned in a dreadful plight, his whiskers were, it is true, of a
jet black, but as the man had touched his face as well as his
whiskers with the dye, be presented a piebald appearance. He
fiercely enquired what would remove the blackness,—the hair-
dresser answered that lie knew of nothing that would remove it,
and there is only one manner of doing it, by means of patience
and pumice stone. The gentleman threatened an action at
law at the time, but his wreath subsided, as the skin wore away.
However skilfully this dye, whether called Tyrian dye, or by
any of its 20 Greek names, is applied it will only change the
colour of the existing hair, and if not continually used, the
roots are continually sprouting of the original red colour. The
oxide of silver is employed as usefully as the Tyrian dye to
communicate a red stain to glass. Immense quantities of this
ichlss are coloured in this manner in London, and almost always
for the purpose of ornamenting those splendid receptacles of
vice, and disease, the London Gin Palaces, and of glazing the
flaming lamps which they suspend over the door.
To analyze silver a very simple process may be resorted to,
when the ore or alloy containing it is dissolved in nitric acid,
by adding a solution of chloride of sodium or common salt, the
silver will be precipitated as chloride of silver. Now nitrate
of silver is so exceedingly delicate a test for the presence of
salt, that if a finger be -dipped into a. solution of it a white
precipitate will be formed arouNl the finger. This arises from
the perspiration from the skin containing a small portion of
common salt. We must use some precaution in testing silver
with chloride of sodium, because a leaden solution will present
the saute appearance, but if we add nitric acid to the solution,
it will be dissolved, which will,not be the case with chloride of
silver. Liquid ammonia will, however, dissolve it. As a col-
lateral test we may apply the solution of the chromate of potass
which will give us a very beautiful crimson precipitate, and as
a collateral test for the presence of gold, we may apply a.solu-
tion of. the pretomuriate of tin, which gives a purple precipitate
called the purple powder of Cassius, which is .used in commu-
nicating a purple colour to glass.
Silver, like gold, is too soft to be generally used by itself, it
is therefore alloyed. The standard alloy of Great Britain_ is
12 1-3 silver, and 1 copper, for domestic artistes, but the alloy
of coin is 11 6z 2 dwt. 'of silver; aaail.lB._ d.vvt._ copper, o.it of
which 66 shillings are fabricated. The process or issa)i, g
silver is like that of gold by cupellation. Nnineious articles
are gilt or silvered to protect them from the atmosphere, or give
them a inure beautiful ' appearance. The general mode of
gilding brass is by way of amalgamation. All articles of brass,
as the interior works of watches, are covered with a solution of
nitrate of mercury, after which they are immersed in a solution
of gold, which forms an amalgam with the mercury, and the
mercury is driven off by heat. Silvering is usually performed
upon copper. Our Birmingham and Sheffield artists perform
this operation better than any others in the world. An ingot of
copper of considerable thickness is soldered to a thin sheet of
silver, the two metals are then passed through rolling mills,
until they are so thin that a single ounce of silver is spread over
three square feet of copper. The f.ice of clocks and barometers
are silvered by tneuns of silvering powder. To make this powder
the silver is first dissolved in nitric acid, and precipitated
by a slip of copper. We then wash this silver precipitate
with ammonia, in order to separate the copper. If this silver
powder be mixed with an equal weight of common salt, cream
of tartar, and alum, and rubbed upon a copper article we shall
have a perfect coating of silver upon it.
To-morrow evening Mr. Hemming will continue the subject
of metallurgy.