SYL 
A to remove all the rest; or if in the 
Aor, all the predicates but one are re- 
itioved, the conclusion must necessarily es- 
tablisli that one. 
, In the several kinds of syllogisms hither- 
to mentioned, we may observe, that the 
parts are complete; that is, the three pro- 
positions of which they consist, are express- 
ed in form. But it often happens, that 
some one of these premises is not only an 
evident truth, but also familiar and in the 
mouths of all men; in which case it is 
usually omitted, whereby we have an im- 
perfect syllogism, that seems to be made 
up of only two propositions : such is the 
following one : 
Every man is mortal ; 
Therefore every king is mortal. 
Here the minor proposition, “ every 
king is man,” is omitted, as being so clear 
and evident, that the reader may easily snp- 
ply it. 
SYLVAN, in mineralogy, a genus which 
is divided into four species; tiz. 1. “The 
native sylvan,” of which the colour is inter- 
mediate between tin white and silver white : 
it occurs massive and disseminated, and also 
in various kinds of crystals : internally it is 
shining, and its lustre is metallic: its specific 
gravity is from 4.1 to 6.1. Its constituent 
parts are 
Sylvan 
Iron 7.20 
Gold O.-g.a 
loo 
Before the blow-pipe it melts as easily as 
lead, emits a thick white smoke, and burns 
with a light green colour, and a sharp dis- 
agreeable odour. When exposed to a low 
heat, it is converted into an oxide : by an 
increase of temperature, it melts into a 
brownish black glass, in which gold grains 
are interspersed : at a still higher heat, the 
oxide is completely volatilized. It occurs 
in veins, and is accompanied with iron py- 
rites, blende, lead-glance, quartz, and litho- 
marge, and is found in Transylvania. It 
bears a strong resemblance to antimony, 
and was formerly called “ auriim proble- 
inaticum white gold ore,” &c. It 
was denominated “ sylvan” by Kirwan, and 
is so called by Jameson, who thinks it more 
expressive than “ tellurium,” a name pro- 
posed by Klaproth. 
2. “ Graphic ore,” which is likewise 
fomtd in Transylvania : it is worked as an 
SYM 
ore of gold, and has obtained the name of 
graphic gold : it consists of 
Sylvan 60 
Gold.... 50 
Silver 10 
100 
It occurs, in veins, in clay porphyiy, accom- 
panied with iron pyrites, grey copper ore, 
blende, and sometimes, though rarely, with 
native gold. Before the blow-pipe it burns 
with a green flame, and is volatilized. 
3. “ Yellow sylvan ore,” which is white, 
inclining to yellow, and is found disseminat- 
ed and crystallized. Specific gravity 10.6. 
It dissolves in nitrous acid, and during the 
solution nitrous gas is evolved ; the consti- 
tuent parts are 
Gold ,.... 
Lead 
Silver 
8.5 
Sulphur 
100 . 
Tliis is found in Transylvania, and is worked 
on account of the prophrtions of the silver 
and gold. 
4. “ Black sylvan ore,’’ which is of an 
iron black colour, and occurs mas.sive, and 
in small, thin, and iongisli six-sided tables ; 
externally it is splendent, wulh a metallic 
lustre: and within it is shining: specific 
gravity is almost 9. Its constituent part* 
are 
Sylvan i8.8 
Lead 24.8 
Gold 4.15 
Silver ; o.25 
Copper 0.6 
Sulphur 1.4 
Oxide of manganese 9.2 
Quartz 43.7 
100 . 
It is found in Transylvania: it melts before 
the blow pipe : the sulphur and sylvan are 
soon volatilized, and a blackish brown glo- 
bule remains, which being melted with bo- 
rax, a sort of silvery gold grain appears. It 
dissolves with effervescence in acids, and 
the nitro-muriatic acid extracts the gold 
from it. 
SYMPHONIA, in botany, a genus of the 
Monodelphia Pentandria class and order. 
Essential character: one styled; corolla 
globular; berry five-celled. There is only 
