SOL 
cylinder, cone, parallelogram, prism, paraL 
lelopiped, &c. 
Solid numhers, ai;e those which arise 
from the multiplication of a plane number, 
by any other whatsoever ; as 18 is a solid 
number made of 6 (which is plane) multi- 
plied by 3 ; or of 9 multiplied by si. 
Solid prohlem, in mathematics, is one 
whicli cannot be geometrically solved un- 
less by the intersection of a circle and a 
conic section ; or by the intersection of two 
other conic sections, besides the circle. 
As to describe an isosceles triangle on a 
given right line, whose angle at the base 
shall be triple to that at the vertex. This 
will help to inscribe a regular hepfagonin a 
given circle ; and may be resolved by the 
intersection of a parabola, and a circle. 
This problem also helps to inscribe a nona- 
gon in a circle, and may be solved by the 
intersection of a parabbla, and an hyper- 
bola between its asymptotes, mz. to de- 
scribe an isosceles triangle, whose angle at 
the base shall be quadruple of that at the 
vertex. And such a problem as tliis hath 
four solutions, and no more ; because two 
conic sections can cut one another but in 
four points. 
SOUDAGO, in botany, golden rod, a 
genus of the Syngenesia Polygamia Super- 
fiua class and order. Natural order of Com- 
posite Discoide®. Corymhifer®, Jussieu. 
Essential character : calyx scales imbricate, 
closed ; corollets of the ray about five ; 
seed down simple, receptacle naked. There 
are thirty species. The golden rods are 
natives of North America, excepting two 
species, which are found in Europe, and 
two others which were discovered by Hou- 
ston in New Spain, and have not been 
adopted by Linnaeus or any other author. 
SOLIDITY, that property of matter, or 
body, by which it excludes all other bodies 
from the place which itself possesses : and 
as it would be absurd to suppose that two 
bodies could possess one and the same place 
at the same time, it follows, that the softest 
bodies are equally solid with the hardest. 
Among geometricians the solidity of a body 
denotes the quantity or space contained in 
it, and is called also its solid content. 
Solidity, in rchitecture, is applied 
both to the consistence of the ground, 
whereon tlie foundation of a building is 
laid ; and to a massive in masonry, of ex- 
traordinary thickness, without any cavity 
within. 
SOLSTICE, in astronomy, that time 
VOL. VI. 
SOM 
when the Sun is in one of the solstitial 
points ; that is, when he is at his greatest 
distance from the equator, thus called, be- 
cause he then appears to stand still, and 
not to change his distance from the equator 
for some time ; an appearance owing to the 
obliquity of our sphere, and which those 
living under the equator are strangers to. 
The solstices are two in each year, the aesti- 
val, or summer solstice ; and the hyemal, or 
winter solstice. The summer solstice is 
when the Sun seems to describe the tropic 
of Cancer, which is on June 22, when he 
makes the longest day ; the winter solstice 
is when the Sun enters the first degree, or 
seems to describe the tropic of Capricorn,- 
which is on December 22, when he makes 
the shortest day. This is to be understood 
as in our northern hemisphere ; for in the 
southern the Sun’s entrance into Capricorn 
makes the summer solstice, and that into 
Cancer the winter solstice. The two points 
of the ecliptic, wherein tlie Sun’s greatest 
ascent above the equator, and his descent 
below it, are ternihiated, are called the sol- 
stitial points ; and a circle, supposed to pass 
through the poles of the world and these 
points, is called the solstitial colure. The 
summer solstitial point is in the beginning 
of the first degree of Cancer, and is called 
the aestival, or summer point ; and the win- 
ter solstitial point is in the beginning of the 
first degree of Capricorn, and is called the 
winter point. These two points are diaine- 
trically opposite to each other. 
flOLUM planfarum, in botany and gar-' 
dening, the natmal soil of plants, or tliat 
which is best adapted to theii' growth. In 
the culture, therefore, of plants, it is of 
importance to have a distinct knowledge of 
those kinds of soil which are adapted to the' 
several genera and species. 
SOLUTION, in chemistry, is the per- 
fect union of a solid substance with a fluid, 
so as apparently to form one homogeneous 
liquid. The fluid is termed the solvent, or 
menstruum, A solution is distinguished 
from a mixture by being perfectly clear, 
and from the particles of the solid not sepa- 
rating from the mass when remaining at 
rest. 
SOMMETI, a mineral named from the 
mountain Somma, where it was first found. 
It is usually mixed with volcanic produc- 
tions. . It crystallizes in prisms, sometimes 
terminated by pyramids. Colour white, 
and somewhat transparent. It cuts glass. 
The specific gravity is 3.27. Infusible by 
O 
