SCH 
SCH 
S. tegulans, or common roof-slate; this IS so peroidese, Jussieu. Essential character: 
soft that it may be slightly scraped with the glumes chaffy, heaped, the outer ones bar- 
nail, and is of a very brittle lameliated tex- ren ; corolla none ; seed one, roundish 
ture: of the specific gravity of 2.8. It is 
fusible per se in a strong heat, and runs into 
a black scoria. By a chemical analysis it 
is found to consist of 
Argillaceous earth 26 
Silex 46 
Magnesia 8 
Lime 4 
Iron 14 
98 
The dark blue slate, or S. seriptorius, con- 
tains more magnesia and less iron than the 
common purple scliistus, and effervesces 
more briskly with acids. Its specific gra- 
vity is 3.7. 2. The pyritaceous schistus is 
of a grey colour, brown, blue, or black ; and' 
capable of more or less decomposition by 
exposure to the air, according to the quan- 
tity of pyritons matter it contains, and the 
state of the iron in it. The aluminous sehis- 
tus belongs to this species. 3. The bitu- 
minous schistus is generally black, and of a 
lameliated texture, of various degrees of 
hardness, not giving fire with steel, but emit- 
ting a sti ong smell when heated, and some- 
times witliout being heated. 
SCHMELZSTEIN, in mineralogy, a sub- 
stance hitherto only found on the Pyrenees, 
where it is imbedded in steatite: it is of a 
greyish-white, passing through the different 
shades to rose red ; it is shining, and its 
lustre is vitreous ; it is easily fiangible. 
Specific gravity 2.6- It swells before the 
blow-pipe. The constituent parts are 
Silica 60 
Alumina 24 
Calcareous earth 10 
Water 2 
Loss 4 
WO 
SCHMIDELIA, in botany, so named in 
honour of Casimir Christopher Schmidel, 
professor of botany at Erlang, a genus of 
the Octandria Digynia class and order. Na- 
tural order of Sapindi, Jussieu. Essential 
character : calyx two-leaved ; ,corolla four- 
petalled j germs pedieelled, longer than 
the flower. There is only one species, 
viz. S.racemosa, a native of the East Indies. 
SCHOENUS, in botany, bog rush, a ge- 
nus of the Triandria Monogynia class and 
order. Natural order of Calamariie. Cy- 
among the glumes. There are forty-one 
species. 
SCHOEPFIA, in botany, so named in 
honour of Johan David Schoepf, a genus of 
the Pentandria Monogynia class and order. 
Natural order of Aggregate. Caprifolia, 
Jussieu. Essential character : calyx dou- 
ble, outer bifid, inferior, inner superior, 
quite entire; corolla bell-shaped; stigma 
capitate ; drupe one-seeded. There is but- 
one species, viz. S. Americana, a native of 
Santa Cruz and Montserrat. 
SCHOLIAST, or Commentator, a 
grammarian, who writes scholia, that is, 
notes, glosses, &c. upon ancient authors, 
wiio have written in the learned languages. 
See the next article. 
SCHOLIUM, a note, annotation, or re- 
mark, occasionally made on some passage, 
proposition, or the like. This term is much 
used in geometry, and other parts of ma- 
thematics, where, after demonstrating a. 
proposition, it is customary to point out- 
how it might be done some other way, or to 
give some advice, or precaution, in order 
to prevent mistakes, or add some particu- 
lar use, or application thereof. 
SCHOKL, in mineralogy, a species of 
the Flint genus; which is divided by Werner 
into two sub-species, viz. the common schorl 
and the tourmaline. The common schorl 
is black. It occurs often massive and dis- 
seminated, seldom in rolled pieces, and 
frequently crystallized. The crystals are 
mostly acicular ; fragments, when broken, 
indeterminably angular ; it very rarely pre- 
sents coarse and small grained distinct con- 
cretion ; sometimes it occurs in very thin, 
and but rarely in thick straight and prismatic 
distinct concretions.- It it opaque, and but 
little translucent on the edges, when it 
passes to the tourmaline. It gives a grey- 
streak ; is hard, and very easily frangible. 
Specific gravity from 3.09 to 3.21. It melts 
before the blow-pipe, without addition, into 
a blackish slag. Melted with borax, it 
forms a greenish coloured glass. It is com- 
posed of 
Silica i 33.33 
Alumina 40.83 
Iron 20.41- 
Manganese.... 3.33 
97.90 
Loss.. 2.10 
100 
