Metals. MINERALOGY. Metals. 
482 
brittle of all the alloys; but the experiments of Mr. 
Bingley and Mr. Hatchet have fhown that this notion is 
to a certain extent erroneous; and that the effe&s pro¬ 
duced by the mixture of tin with gold, ought probably 
to be alcribed to other metals, with which the tin was 
contaminated, fuch fs bifmuth, antimony, lead, and zink. 
The alloy, confuting of equal parts of zink and gold, is 
very hard, and fufceptible of a fine polifh; and, not being 
fubjeft to much alteration from the air, it is recommended 
for the fabrication of the mirrors of telefcopes. The al¬ 
loy of gold with filver, in which there is only J^th part 
of filver, changes the colour of the gold very fienfibly ; 
and this alloy is employed for foldering gold, being more 
fuiible than that metal. Phil. Tranf. 1803. 
The weight of gold is to that of water, according to 
fome ftatements, as 19-637 to rooo. Fine gold, immerfed 
in water, weighs nearly one-nineteenth part lefs than in 
air, and confequently it is upwards of nineteen times 
heavier than its own volume of water. However, the 
fpecific gravity of gold, or its comparative weight with 
an equal volume of water, has been varioully affigned: 
fome have made it i9'637, others 19-640; and in the Swe- 
difh Tranfabtions it is made no lei’s than 20-000 ; others 
again have made it as low as 18-75. But from the expe¬ 
riments of Mr. Ellicot, it does not appear to have exceeded 
19-207 ; and from thofe of Dr. Lewis, on the pureft gold, 
well hammered, its gravity is ftated between 19-300 and 
19-400. If the mean gravity of gold be reckoned 19-300, 
as a cubic inch of water weighs about 254 grains, a cubic 
inch of gold will confequently weigh about 4902 grains, 
or 10 ounces 102 grains. The pound weight, or twelve 
ounces troy, of gold, is divided into twenty-four carats. 
Dr. Lewis ftates the l’pecific gravity of fine gold, at 53 0 
Fahrenheit,' to be 19-376. According to Briffon, the fpe- 
cific gravity of fine gold in ingot is 19-258, and when 
hammered 19-361. The l'pecific gravity of gold made 
ftandard by Britifii copper, was found by Mr. Hatchett 
to be 17-281, when call in an iron mould; but; when the 
fame was call in land, it was only 16-994. The foftnel’s 
of gold, for it is nearly as loft as tin, and its toughnefs, 
adapt it for receiving the imprefiions of dies, and of courfe 
to be reduced to the ftate of coin, and for various other 
purpofes in the arts. It is but flightly elallic and fono- 
rous. With regard to tenacity, it is inferior to iron, cop¬ 
per, platina, and filver; and therefore the aifertions of for¬ 
mer chemifts and philofophers have been contradicted by 
inter experiments, for gold has been ufually represented 
as the molt tenacious as well as the molt duCtile of all 
metals. 
The value of gold to that of filver was anciently only 
as twelve to one. Indeed, this proportion varies as gold 
is more or lefs plentiful: for Suetonius relates, that Csefar 
brought fuch a quantity of gold from Italy, that the 
pound of gold was worth only feven pounds and a half 
of filver. In our coinage, the value of fine gold to fine 
filver is nearly as 15^ to 1. (See Medal, vol. xiv. p. 808.) 
Sir Ifaac Newton obferves, in a reprefentation to the 
lords of the trealury in the year 1717, that in the mints 
of Spain and Portugal the value of gold is fixteen times 
that of filver; but that in thofe countries, payments in 
filver bearing generally a premium of fix per cent, the 
proportion may be confidered as fixed by commerce at 
15^V to 1; that in the other parts of Europe, the value of 
gold is at moll fifteen, and in China and Japan but nine 
or ten, times that of filver; fo that gold is rated higher in 
England than in any other part of Europe, and higher in 
Europe than in the eaftern countries. Hence, in great 
mealure, arife the profits of exchanging gold for filver in 
one place, and re-exchanging them in another ; and hence 
the greater dil'parity between the relative quantities of 
gold and filver in one commercial nation than in another; 
this metal being brought in moll abundance which is 
rated highelt in proportion to the other, and that which is 
rated loweft being drained away. 
There are various ways of determining the finenefs of 
gold; or the proportion of alloy which it contains. Thofe 
who are ufed to this bufinefs can judge nearly the pro¬ 
portion of alloy from the colour of any given mafs, pro¬ 
vided that the fpecies of alloy be known. The great ex¬ 
cels of the weight of gold, above that of the metals ufed 
for its alloy, affords another method of determining the 
quantity of alloy in any given mafs, where the lpecfes of 
alloy is known. Thus fine gold lofes in water one grain 
in every 19-3 nearly; and fine filver lofes one grain in 
about eleven ; from whence it is eafy to find the lofs of 
any number of grains of each, and confequently of any 
affignable mixture of the two metals. Thus, fifty grains 
of gold will lofe above 2f, and fifty grains of filver l'ome- 
what more than 4! ; fo that a mixture of equal parts of 
the two will lofe above feven in a hundred, or one in four¬ 
teen. A mixture of gold with half its weight of filver 
will lofe one part in 15-4; with a third of filver, one in 
16-2 3 with a fourth, one in 167 ; and with an eleventh of 
filver, which is the ftandard proportion of alloy, one in 
18-1. On this principle, the l'pecific gravity, or propor¬ 
tional lofs in water, of gold alloyed with different quan¬ 
tities of filver, copper, and mixtures of both, may be com¬ 
puted and formed into tables for ufe. The accuracy of 
this method, it Ihould be obferved, depends on the l'up- 
pofition that each of the two metals, tiiat are melted to¬ 
gether, retains its own proper gravity, which is the cafe 
in mixtures of gold and filver; but gold and copper, 
melted together, are fpecifically lighter than if they were 
weighed leparately; or the l'pecific gravity of the alloy is 
lefs than that of the mean of its ingredients; the caie is 
the fame with the alloys of nickel and gold, of lead and 
gold, of iron and gold 5 but the reverie happens in mix¬ 
tures of gold with zink, bifmuth, and tin. It appears, 
therefore, that the hydroftatic balance cannot dilcover, 
with certainty, the exaft finenefs of gold, unlefs when 
filver is the metal mixed with it. 
2. Aurum arenareum, or landy gold : combined with 
grains or particles of fand or other lubftances, and giving 
them a golden fplendour. Found in many rivers of South 
America and the adjacent illands ; in Africa, Arabia, In¬ 
dia, and many parts cf Europe; more or lefs ponderous, 
and containing gold in greater or lefs quantities, fiome- 
times fo fmall as not to be worth working. 
3. Aurum larvatum, or malked gold: intermixed with 
other follils in very minute particles, which are feparable 
by means of quickfilver. Found in the mines of Siberia, 
Tranfylvania, Hungary, Saxony, Sweden, and America, 
combined with chalk, fpar, alumine, lliiftofe porphyry, 
jafper, quartz, antimony, arlenic, &c. and is l’ometimes 
made whitiih by various combinations of lead, fpatofe 
iron ore, or fulphat of iron, copper, or filver. The parti¬ 
cles of gold are rarely vifible to the naked eye. 
4. Aurum platinatum, or platinum-gold: yellowilh- 
grey, in fmall grains; harder and heavier than pure gold. 
Found in Spanilh America, in fmall grains, involved in 
the platinum ; and may be difunited by diffolving the 
platinum in nitro-muriatic acid, and adding muriat of 
ammonia, which precipitates the platinum and leaves the 
gold in 1'olution. 
5. Aurum argentiferum, or filvery gold ; of a pale yel¬ 
low colour; lighter than pure gold. Found in molt gold¬ 
mines, fometimes combined with nearly a fourth part of 
filver, in fmall particles or laminae, filaments or fix-lided 
plates, leldom in large pieces, but ufually difperl’ed though 
certain Hones. 
6. Aurum molybdeni, or molybdenic gold: ftaining 
the fingers; of a lead colour and luftre: emitting flame 
and fuiphurous vapours when burnt, and in a very vio¬ 
lent heat leaving a button of pure gold. Found in the 
mines of Nagyag in Tranfylvania, and in thofe of Hun¬ 
gary near Rimazombat, and conlifts of various propor¬ 
tions of gold, oxyd of molybdenum, and fulphur. 
7. Aurum ftibiatum, or antimoniated gold : of a fteel- 
yellow colour; emitting fuiphurous vapours and flame 
with a white linoke, when heated to whitenel's. Found 
3 near 
