C H E M I 
lofes about the eleventh part of its weight by immerfion 
in water, and a cubic foot of this metal weighs 720 
pounds. Silver is fo duftile, that it may be beat into 
exceedingly thin leaves, and drawn into wire much finer 
than a hair. A grain of leaf filver meafures fomewhat 
more than fifty-one fquare inches, and the filver wire, 
ufed by aftronomers, about the 750th part of an inch in 
diameter. This is about half the diameter of a fine hu¬ 
man hair. A grain of filver may be extended fo as to 
form a veflel capable of containing an ounce of water. 
Its tenacity is fo confiderable, that a filver wire of the 
tenth of an inch in diameter, may fultain a weight of 
270 pounds without breaking. Its hardnefs and elaiticity 
are not equal to thofe of copper. It is the moll fonorous 
of metals after thofe we have mentioned. It hardens 
under the hammer, but very readily loles that hardnefs 
by heating. 'Fillet and Mcngez have cryftallized this 
metal, and obtained quadrangular pyramids, fometimes 
infulated like thofe which are found on the edges of the 
crucibles in which this metal has been melted, or group¬ 
ed and laterally placed one on the other. 
The only way of obtaining pure filver, much finer than 
that obtained by cupellation, is to extraft it frommuriat 
of filver. Silver fuitains almoft a white heat previous to 
fufion; and, in a very violent fire, it will volatilize. It 
oxydates with the greateft difficulty, by the combined 
aflion of heat and air ; but the eleftxic lpark haftens the 
oxydation.: Air feems to have no action upon this metal; 
yet the furface will be tarnifhed by long' expoiure. 
To produce pholphorated filver, take one part of 
pholphoric glafs, one half part of filings of filver, and 
of charcoal in powder one half of the weight of the 
filver. Put thefe together in a crucible, and expofe 
them to the heat of a melting-furnace for half an 
hour. When the fufion is complete, the filver is leen at 
the bottom of ihe crucible, and little bubbles of phof- 
pliorus are difengaged : take off the crucible immediate¬ 
ly, and let it in the air, that it may cool quickly. The 
filver foon becomes folid, and fome fprigs of phofphorus 
may be taken out of the metallic button. The weight 
of the filver is increafed, its duftility diminiffied; it ap¬ 
pears grained and cryftallized, and breaks under the 
hammer. Expofed on a cupel in a hot muffle, the phof- 
phorus is diflipated, and the filver remains pure. 
Sulphur combines readily with filver; this combination 
is ufually made by ftratifying plates of the metal with 
flowers of fuiphur in a covered crucible, and quickly 
fuflng the mixture: a deep violet coloured mafs is pro¬ 
duced, much more foluble than filver, brittle, and dif- 
pofed in needles ; in a word, a true artificial ore of filver, 
or fulpliurated filver, is produced. The Germans call it 
blanchmal, on account of its refembling certain ores of 
filver which they call by that name. Some filver ores 
may be imitated by adding a little arfenic ; this produces 
a reddilh mafs, fomewhat like the native red ore of filver. 
The artificial fulphure of filver is eafily decompoled by 
the a£tion of fire, becaufe of the volatility of the fuiphur 
and the fixity of filver; the fuiphur is confumed and 
diffipated, and the filver remains pure. Alkaline fulphure 
difiolves this metal in the dry way. When one part of 
filver is melted with three parts of fulphure of potafli, 
the metal difappears, and becomes foluble in water, to¬ 
gether with the fulphure. If an acid be poured into this 
iolution, a black fulphurated precipitate of filver is ob¬ 
tained. Silver left in a folution of fulphure of potafh, 
quickly affumes a black colour, and the fuiphur appears 
so quit the alkali to unite with and mineralize the metal, 
as we have likewife obferved it does with mercury. 
Silver unites with arfenic, which renders it brittle; 
but the properties of this mixture are not yet known. It 
does not combine with cobalt without difficulty. It 
unites perfectly well with bifmuth, and forms a brittle 
mixed metal, whofe fpecific gravity is greater than that 
of the two metals feparately taken. According to Cron- 
fledt, filver does not unite with nickel j but when theie 
Vol. IV. No. 198. 
S T R Y. 3© 9 
metals are melted together, they remain befide each other, 
as if their fpecific gravity were piecifely the fame. It 
mixes by fufion with antimony, and affords a very brittle 
alloy. It feems capable of decompofing fulphure of an¬ 
timony, and of uniting with the fuiphur of that mineral, 
with which it has a ftronger affinity than the antimony. 
Silver combines readily with zink by fufion; an alloy 
is produced by this combination, granulated at its fur- 
face, and very brittle. It difiolves completely, and even, 
without heat, in mercury. To produce this folution, 
filver leaf may be triturated with feven timers its weight 
of the metallic fluid; an amalgam is produced, whofe 
confidence varies according to the relative quantities of 
the two fubftances. Or, fine filings of filver may be ufed, 
in which cafe itfhould be powdered in a warm mortar with 
the mercury. This amalgam is capable of alTuming a 
regular form ; by fufion and flow cooling, it affords te¬ 
trahedral prifmatic cryftals, terminated by pyramids of 
the fame form. The mercury aflumes a degree of fixity 
in this combination ; for a much ftronger heat is necel- 
fary to feparate it from the filver, than would be required' 
to volatilize it alone. Silver is capable of decompofing 
corrofive mercurial muriat, either by the dry or the hu¬ 
mid way. I.t unites perfedlly with tin, but lofes its duc¬ 
tility by the fmalleft addition of this metal. It readily 
becomes alloyed with lead, which renders it very fufible, 
and.deprives it of its elafticity and fonorous quality. It 
unites with iron, and forms an alloy, which has been 
,but little examined into, but may probably become of 
the greateft utility in the arts. It melts and combines in 
all proportions with copper; and may be even combined 
in equal quantities with filver, without fenfibly changing 
the colour of that metal. Copper gives body, ftiffhefs, 
and elafticity, to filver; but conliderably diminifhes its 
du&ility. Copper is the alloy mixed with filver in mak¬ 
ing plate and money : without this, the filver would not 
be hard enough to refill its wear and ufe. . 
Almoft all combuftible matters have a certain aflion on 
filver; no metal is more quickly tarnifhed and coloured 
by inflammable matters ; fulphurated hydrogen gas, from 
whatever fubftance it may be difengaged, communicates 
to it immediately upon contact, a blue or violet colour, 
inclining to black, and greatly diminifhes its du&ility. 
It is well known that fetid animal vapours, fuch as thole 
of neceffary houfes, putrified urine, and hot eggs, pro¬ 
duce the fame efteft on this metal. 
The aflay of filver ores varies according to their na¬ 
ture; fuch as contain native filver ore, require nothing 
more than feparating and waffling. Trituration with 
running mercury may be ufed for the accurate feparating 
of this metal from the marine fubftances, which change 
it; the fluid metal difiolves the filver, and may be after¬ 
wards driven off by fire. Sulphureous filver ores require 
to be roafted, and afterwards melted with a greater or 
lefs quantity of flux ; in this fufion, filver is obtained 
commonly alloyed with lead, copper, iron, &c. For the 
feparation and accurate afeertaining of the quantity of 
pure metal contained in this alloy, a procefs entirely che¬ 
mical is ufed, which depends on the properties of the 
other metals. Lead being capable of vitrifying, and of 
carrying with it in its vitrification the iron and copper, , 
without acting on filver, this property is ufed to feparate 
the filver from thofe with which it is alloyed ; the filver 
is melted with a quantity of lend, which muft be fo much 
the more confiderable, in proportion as the quantity of 
bafe metal is fuppoled to be greater. This alloy is then 
put in flat and porous vefiels, made of calcined bones and 
water ; this kind of crucible, which is called a cuppel , is 
well adapted to abforb the glafs of lead, ufually formed 
in cuppellation. After this procefs, the filver remains 
pure. In order to determine what quantity of bale metal 
it contains, or its degree of fineneis, the mafs of filver is 
ftippofed to be divided into twelve parts, called penny¬ 
weights, and each of thefe pennyweights into twenty-four 
grains ; if the mafs of filver has loft a twelfth of its 
4K. Weight, . 
