SIL 
and evaporated, another yellow silky salt 
separates, which detonates on coals like 
common nitre, and appears to be a triple 
combination of the former bitter substance 
with nitrate of potash. 
SILPHA, in natural history, the carrion 
teetle. Antennae clavate ; the club perfo- 
liate ; shells margined ; head prominent ; 
thorax somewhat flattened margined. There 
are about 140 species, divided into sections. 
A. Lip dilated, bifid ; jaw one-toothed. 
B. Lip rounded entire; jaw one-toothed. 
C. Lip horny, entire ; jaw bifid. D. Lip 
emarginate, conic ; jaw bifid. E. Lip heart- 
shajjed, emarginate, crenate. F. Lip square, 
emarginate. G. Lip long, entire ; antenna: 
serrate. H. Lip and jaw unknown. The 
insects of this genus are usually found among 
decaying animal and vegetable substances ; 
frequenting dunghills, carrion, &c. and de- 
posit their eggs chiefly in the latter. The 
larvae are of a lengtliened shape, roughened 
with minute spines and protuberances. S. 
vespillo is the most remarkable among Eu- 
ropean species: this is not uncommon in 
our own country. This animat is about 
three quarters of an inch long, and is dis- 
tinguished by having the wing-sheatlis con- 
siderably shorter than the abdomen. It seeks 
some decaying animal substance in which 
it may deposit its eggs, and for the greater 
security contrives to bury it under ground. 
Sometimes three or four insects, working in 
concert, have been known to drag under 
the surface the body of a mole in the space 
of an hour, so that no trace of it has ap- 
peared above ground: the eggs are white 
and oval : from these are hatched the larvre, 
which, when full grown, are more than an 
inch long. Each larva forms for itself an 
oval cell in the ground, in which it changes 
to a yellowish chrysalis, resembling that of 
a beetle, out of which, in somewhat less 
than three weeks, proceeds the perfect in- 
sect. This species diffuses a strong and un- 
pleasant smell; it flies with considerable 
strength and rapidity, and is generally seen 
on the wing during the hottest part of the 
day. 
SILPHIUM, in botany, a genus of the 
Syngenesia Polygamia Necessaria class and 
order. Natural order of Composite Op- 
positifoliic. Corymbiferae, Jussieu. Essen- 
tial character : calyx squarrose ; seed down, 
margined, twohorned; receptacle chaffy. 
There are eight species. 
SILVER, which is divided by mineralo- 
gists into three’ species,, the native, antiuio- 
pial^ and the arsenical, has been reckoned 
SIL 
among the noble or perfect metals, and has 
been known from the earliest ages of the 
world. Its scarcity, beauty, and utility, 
have always rendered it an object of re- 
search among mankind, so that the nature 
and properties of this metal have been long 
studied and minutely investigated. In the 
midst of the rage for the transmutation of 
metals which for centuries fired the imagi- 
nations of the alchymists, silver occupied a 
great share of their attention and labour, 
with the hope of discovering the means of 
converting the baser and more abundant 
metals into this, which is more highly valued 
on account of its scarcity and durability. 
When the dawn of science commenced, and 
its light had dissipated the follies and extra- 
vagancies of tliese pursuits, the earlier che- 
mists were much employed in examining 
the properties and combinations of silver; 
nor has it been overlooked or neglect- 
ed by the moderns. Silver, which is neither 
in such abundance nor so universally dif- 
fused as many other metals, exists in nature 
in five different states : in the native state ; 
in that of alloy with other metals, especially 
with antimony ; in that of sulphuret, sulphu- 
rated oxide, muriate, and carbonate. 
1. Native silver, which is characterized 
by its ductility and specific gravity, is fre- 
quently tarnished on the surface, of a grey 
or blackish colour, and appears und'er a 
great variety of forms. In this state it is 
not perfectly pure. It is usually alloyed 
with a little gold or copper. 
2. The alloy of silver and antimony, which 
is the most frequent, is distinguished by its 
brittleness and lamellated structure from 
native silver, which it resembles in lustre 
and colour. It crystallizes in prisms, which 
are six-sided, and pretty regular. 
3. The sulphuret of silver, which is known 
to mineralogists by the name of vitreous 
silver ore, is of a dark grey colour, and has 
some metallic lustre. It is usually crystal- 
lized in the form of cubes, octahedrons with 
angular facets, or sometimes in the form of 
the dodecahedron. 
4. The sulphurated oxide of silver and 
antimony. In this ore of silver the sulphur 
is combined with the metal in this state of 
oxide; in the former, in the metallic state. 
This ore is called red silver ore. It is of a 
deep red colour, sometimes transparent, 
and sometimes nearly opaque, frequently 
having the lustre of steel on the surface. 
The primitive form of its crystals is the 
rhomboidal dodecahedron. 
5. The muriate of silver, which has been 
