SPA 
by its positions to bodies within it, and this 
is the vulgar use for immoveable space. 
Relative space, in magnitude and figure, is 
always the same with absolute ; but it is 
not necessary it should be so numerically ; 
as if you suppose a ship to be, indeed, in 
absolute rest, then the places of all things 
within her will be the same, absolutely and 
relatively, and nothing will change its. 
place : but suppose the ship under sail, or in 
motion, and she will continually pass through 
new parts of absolute space ; but all things 
on board, considered relatively in respect 
to the ship, maybe, notwithstanding, in the 
same places, or have the same situation and 
position in regard to one another. 
Space, in geometry, denotes the area of 
any figure, or that which fills the inter- 
val or distance between the lines that ter- 
minate it. 
Space, in mechanics, the line a moveable 
body, considered as.a poipt, is conceived to 
describe by its motion. 
SPADIX, in botany, a term formerly ap- 
plied to the receptacle of the palms : it is 
now used to express every flower stalk that 
is protruded out of a spatha or sheath. 
SPAN, a measure taken from the space 
between the thumb’s end and the tip of the 
little finger, when both are stretched out. 
The span is estimated at three hand’s 
breadths, or nine inches. 
Span, in naval affairs, a small line or 
cord, the middle of which is usually attach- 
ed to a stay, whence the two ends branch 
outwards to the right and left, liaving eitlier 
a block or thimble attached to their extre- 
mities. ' 
SPAR; a name given to those earths 
which break easily into rhomboidal, cubi- 
cal, or laminated fragments, with polished 
surfaces. As the term spar is thus applied 
to stones of different kinds, wdthout any 
regard to the ingredients of which they are 
composed, sorpe additional terra must be 
used to express the constituent parts as 
well as the figure. The spars found in 
Britain and Ireland are of four different 
species ; opauiue, refracting, diaphanous, 
and stalactical. A species of spar has 
also been found in the East Indies, which, 
from its extreme hardness, approaching to 
that of a diamond, is called adamantine 
spar. It was discovered by Dr. Black, of 
Edinburgh, to be a distinct species. There 
are two varieties ; one of them comes from 
China, and crystalizes in hexagonal prisms 
without pyramids, the length of the sides 
SPA '' 
varying from six to twelve lines, their 
breadth being about nine, of a grey colour 
with different shades. Though the entire 
pieces are opaque, tlie thin lamm® are 
transparent, and when broken, its surfaces 
appear slightly striated. Its crystals are 
covered with a very fine and strongly ad- 
hering crust, composed of scales of silvery 
mica, mixed with particles of red felspar. 
Sometimes the surface has martial pyrites 
or yellow sulphuret of iron adhering to it. 
Its hardness is so great, that it not only 
cuts glass as easily as the diamond, but 
even scratches rock crystal and other very 
hard stones. Its specific gravity is to that 
of water as 2.7 to 1.0. Sometimes it con- 
tains crystalized grains of magnetic oxide 
of iron, which may be separated from the 
stpne, when pidverised, by means of the 
loadstone. The otirer kind, found in Ilin- 
doostan, is of a whiter colour, and of a 
more laminated texture than tlie former. 
The grains of iron contained in it are like- 
wise a smaller size than those of the for- 
mer j they are not diffused through its 
substance, but only adhere to its surface. 
This spar is exceedingly difficult to analyze. 
M. Morveau appears to have ascertained 
that this stone is also found in France. A 
small bit of it was tried in the presence of 
Mr. Wedgewood, and he found that its spe- 
cific gravity was superior to the spar of 
China, being no less than 4,18, and the 
true adamantine spar of China gave 3.82. 
Although the word spar seems to include 
almost all the earthy crystalized minerals 
that are met with in metallic veins ; yet 
mineralogists liave generally agreed to ap- 
ply the term to those minerals, whether 
earthy or metallic, which are crystalized, 
and have a visible foliated texture. Hence 
we have felspar-spar, fluor-spar, &c. Seme 
of the spars have already been described in 
their alphabetical order; others we shall 
enumerate here. 
Spar, cube, is of a milk-white colour, 
which passes sometimes into a greyish-white, 
and even into a reddish-white. It is mas- 
sive ; the lustre is shining, passing to splen- 
dent, and perfectly pearly. The fragments 
are cubical. Specific gravity is 2.9. It is 
found in salt rocks in the Archbishopric of 
Salzbourg. 
Spar, diamond, is of a dark brown co- 
lour ; it occurs massive, disseminated, in 
rolled pieces, and crystalized in six sided 
prisms and pyramiJs ; mternaliy its lustre is 
splendent, and generally pearly, approach- 
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