SIL 
application of heat, and even when it is ex- 
posed to the light. By heating it in close 
vessels, pure oxygen gas is obtained, and 
the metal is converted to the metallic state, 
by melting it in a crucible. 
Silver combines with phosphorus, form- 
ing a phosphuret. One part of silver in til- 
ings, with two of phospboi'ic glass, and 
half a part of charcoal, exposed to heat in 
a crucible, yielded a phosphuret ot silver 
which had acfjuired one fourth of its primi- 
tive weight of silver. This phosphuret is ot 
a white colour, brittle, of a granulated 
texture, and may be cut with a knife. By 
throwing pieces of phosphorus on silver red 
hot in a crucible, the metal is instantly 
melted, and the phosphuret which is formed 
remains at the bottom. At the moment 
when the surface becomes solid, a quantity 
of phosphorus is thrown out with a kind of 
explosion, and the surface of the metal 
then exhibits a maniellated appearance. 
Pelletier, wdio first made this experiment, 
concludes from it, that silver is susceptible 
of retaining a greater proportion of phos- 
phorus, in combination with it, when it is in 
fusion, than in the solid state, and that the 
separation of the phosphorus is owing to the 
sudden contraction of the silver. A hun- 
dred parts of silver in fusion retain twenty- 
five of phosphorus, but only fifteen when it 
becomes solid. 
Phosphorus has the property of reducing 
the oxides of silver, and of precipitating 
them from this solution in acids, in the me- 
tallic form. Sulphur combines readily with 
silver, both in the dry and humid way. By 
stratifying in a crucible, plates of silver 
alternately with sulphur, and melting them 
rapidly, a deep violet-coloured mass is ob- 
tained, which is more fusible than silver, 
brittle, crystallized, and has a metallic lus- 
tre. It may be cut with a knife, ami has a 
good deal of resemblance to vitreous ore of 
silver. When this sulpburet of silver is ex- 
posed to heat for a considerable time, the 
sulphur is gradually dissipated, and the sil- 
ver remains pure and ductile. Silver com- 
bines very readily with sulphur, when it is 
long exposed to those matters which gra- 
dually deposit tliis substance. This effect 
is immediately produced when silver is 
brought into contact with sulphurated hy- 
drogen gas, or when it is immersed in wa- 
ter impregnated with this gas, as in natural 
sulphureous waters. Dr. Thomson thinks 
it is owing to the same cause that a silver 
spoon is tarnished by a boiled egg, and par- 
ticularly if the egg has begun to spoil. 
SIL 
Sulphureted hydrogen gas, which is ex- 
haled by the egg, is decomposed ; the sul- 
phur combines with the- silver, and forms a 
thin layer of sulphuret of silver, which is 
of a dark or violet colour; other writers 
have ascribed this to the action of galvan- 
ism. The same thing happens when silver 
is exposed in places that are much fre- 
quented, as in churches and theatres. Sil- 
ver forms alloys with most of the metals, 
and salts with the acids. Hence its use in 
coinage, and also in medicine. 
Antimonial silver, in colour, is between 
silver white and tin white ; sometimes in- 
clining more to the one, sometimes more to 
the other. It occurs massive, dissemi- 
nated, and crystallized. Specific gravity be- 
tween 9 and 10. Heated on charcoal before 
the blow pipe, the antimony is volatilized 
with the odour peculiar to it, and there re- 
mains a mass of silver, surrounded with a 
brown slag. It consists, according to Vau- 
quelin, of 
Silver 78 
Antimony •••••_££ 
100 
It occurs in veins which are composed of 
calc-spar, heavy-spar, and is accompanied 
with lead glance, and native silver. It is 
distinguished from native silver by its bi it- 
tleness, and a foliated fracture. 
Arsenical silver is of a tin white colour, 
which passes into silver white, and verges 
.on light lead grey. It is always more or 
less tarnished with a blackish colour. It 
occurs massive, disseminated, and globular. 
It consists of 
Arsenic 35 
Iron 44.25 
Silver 12.75 
Antimony 7 
too 
Before the blow pipe the arsenic and an- 
timony are volatilized, and they emit a gar- 
like smell. The silver remains moie or less 
pure in shape of a globule. This is a very 
rare mineral, and does not tarnisli so quick- 
ly as native arsenic ; it passes on the one 
side into native arsenic; on the other into 
native silver. 
SILVERING, in the arts, consists in co- 
vering the surfaces of substances witli a thin 
coating of silver ; either for the purpose of 
beauty, silver being so much more hand- 
some than the inferior metals ; or, on ac- 
