S M A 



[408 ] 



SOL 



the only existing genus of Tardi- 

 grada. 



SMALT, (smalto, It. schmalte, Germ.) 

 Powder-blue, a vitreous substance 

 obtained by melting zaffre, silex, 

 and potash together, 

 SMAKA'GDITE. The name given by 

 Saussure to diallage, from its eme- 

 rald-green colour. 



SMA'HAGD. | (from fffidpa^Sos, Gr.) 

 SMA'BAGDUS. j The emerald. See 



Emerald. 



SOAP EOCK. | Names given to a kind 

 SOAP STONE. ) of steatite, in conse- 

 quence of its soapy feel. Soap rock 

 is so tender that it may be cut as 

 easily as new cheese. Its colour is 

 a pearly white or grey with red and 

 blue veins, and when pure is semi- 

 transparent. On coming out of the 

 quarry, it may be kneaded like a 

 lump of dough, but after having 

 been exposed to the air for some 

 time, it becomes friable ; it possesses 

 the soapy feel in the highest degree. 

 It is used in the manufacture of 

 porcelain. Klaproth gives the fol- 

 lowing as the analysis of soap rock: 

 silica 48-00, magnesia 20-50, alu- 

 mina 0'14, iron 0-01, water 15-50. 

 SO'DA. (soda, sode, soude, Germ.) 

 Mineral fixed alkali, found native 

 in some situations, but generally 

 obtained from the combustion of 

 marine plants, more particularly of 

 the salsola soda. " Soda," says De 

 la Beche, "is found in schorl, and 

 certain hypersthene rocks, in some 

 eurites, in trachytes, pitchstones, 

 basalts, and some diallage rocks. 

 It is found in greatest abundance 

 diffused through the waters of the 

 ocean." 

 SO'DA FE'LSPAB. Another name for 



albite. See Allite. 

 SO'DALITE. (from soda, and X/0os, 

 Gr. stone.) A sub species of lapis 

 lazuli. The name sodalite has 

 been given to this mineral from the 

 large proportion of soda which it 

 contains, being 25 per cent. Its 

 constituents are silex 36 % 0, alumine 



32-0, soda 25'0, muriatic acid 6-7, 

 oxide of iron 0-2. It is found in 

 Greenland and Vesuvius. It occurs 

 massive, and in dodecahedrons with 

 rhombic faces. Colour green, of 

 different shades. Structure foli- 

 ated; fracture conchoidal. Specific 

 gravity 2'37. It is infusible. 

 SO'DIUM. One of the simple or ele- 

 mentary bodies. Sodium is the 

 metallic basis of soda, and, like 

 potassium, was discovered by Sir 

 H. Davy in 1807. It has the 

 appearance of silver, or of lead, 

 and is both ductile and malleable. 

 Its specific gravity is 0'97, conse- 

 quently it is lighter than water. 

 When united with oxygen in the 

 proportion of 23-3 by weight to 8 

 oxygen, it constitutes soda. 

 SOIL, (sol, Fr. souk, It.) The name 

 given to that superficial accumu- 

 lation of various substances which 

 lies upon the surface of the globe, 

 and covers the rocks below ; it is 

 also called earth, mould, loam, &c. 

 Its depth is irregular, from a few 

 inches to several feet. 

 SOLA'NOCRINITES. A genus of Kadi- 

 aria, three species of which have 

 been determined by Gold fuss and 

 Munster; these have been found 

 in the oolitic group of Germany. 

 SOLATIUM. A genus of fossil and 

 recent depressed, conical, nearly 

 discoidal, umbilicated, marine, uni- 

 valve shells, belonging to the 

 family Turbinacea. Recent solaria 

 are littoral shells, found on rocks 

 and weeds, and belong to tropical 

 seas. 



SO'LEN. A genus of marine bivalves, 

 found on sandy beaches, wherein 

 it burrows vertically, and lies con- 

 cealed at a depth of about six 

 inches, when the tide leaves the 

 beach dry. The shell is bivalve, 

 oblong, equi valve, inequilateral, 

 open at both ends ; hinge with a 

 subulate reflected tooth, often 

 double, and not inserted in the 

 opposite valve. 



