SAL 



L 391 ] 



SAP 



a salt by combination with some 

 other body ; capable of combining 

 with an acid to form a salt. 



SA'LIVABY GLANDS. Organs which 

 secrete the saliva. All aniiaals 

 that masticate their food are pro- 

 vided with salivary glands, which 

 pour the saliva into the mouth as 

 near as possible to the grinding 

 surfaces of the teeth. Pishes and 

 the cetacea, performing no masti- 

 cation, have no salivary glands. 



SALT, (sal, Lat. safe, Germ.) In 

 an impure state, one of the most 

 abundant productions of nature. It 

 occurs in two forms, either as a 

 solid mineral, or in solution, in the 

 waters of the ocean, and of lakes 

 and springs in inland districts. The 

 waters of the ocean contain about 

 one-thirtieth of their bulk in solu- 

 tion. The uses of salt are nume- 

 rous, putting aside its great im- 

 portance, or absolute necessity, as 

 a matter of food. It is employed 

 in glass-making, enamelling, glaz- 

 ing, and bleaching. It is a valuable 

 manure ; and is used in the making 

 of bread. Although the most fre- 

 quent position of rock-salt is in 

 strata of the new red sandstone 

 formation, yet it is not exclusively . 

 confined to them. The salt mines 

 of Wieliezka and Sicily are in ter- 

 tiary formations ; those of Cardona 

 in cretaceous; some are found in 

 the oolite; while others occur in 

 the coal formation. 



SAND, (sand, Germ.) Flint or quartz 

 broken fine by the action of water, 

 but not reduced to powder. Yery 

 small particles of silicious matter 

 not cohering together, nor softened 

 by water. 



SA'NDSTONE. An aggregate of sili- 

 cious grains. Any stone composed 

 of grains of sand agglutinated 

 together. The grains of sandstone 

 are sometimes so fine as scarcely to 

 be distinguished by the unaided 

 eye ; at others their magnitude is 

 equal to that of a walnut or an egg, 



as in the coarse sandstones known 

 as conglomerates, pudding-stones, 

 breccias, &c. The cement which 

 agglutinates the silicious particles 

 of sandstones may be calcareous, 

 argillaceous, or silicious : when 

 silicious the sandstone sometimes 

 resembles quartz. Sandstones are 

 close, porous, and vesicular, with 

 every intermediate gradation, from 

 perfectly loose sand to the hardest 

 sandstone. They vary in colour, 

 from white to red or * brown, but 

 their most common colour is grey 

 or greyish white : sometimes their 

 colour is uniform, at others it is 

 variegated. 



SA'PPAHE. A mineral first described 

 by Saussure. The Cyanit of Wer- 

 ner, and Disthene of Haiiy. 



SA'PPHIEE. (from acnrfaipo's, Gr. sap- 

 phirus, Lat.) A precious stone, 

 exceeding all others in hardness 

 except the diamond. It occurs 

 crystallized, in six-sided prisms 

 variously terminated ; the crystals 

 yield readily to cleavage in one 

 direction, presenting a most bril- 

 liant surface ; cleavage fourfold ; 

 fracture conchoidal. It consists of 

 nearly pure alumina, with a little 

 oxide of iron, with some silex or 

 lime; but the sapphire contains 

 upwards of ninety- eight per cent, 

 of alumina. Its specific gravity is 

 from 3-70 to 4'30. It possesses 

 double refraction, and varies from 

 opaque to transparent. Its colours 

 are blue, red, green, white, grey, 

 yellow, brown, and black. There 

 are several varieties of the sapphire, 

 as the white, blue, or oriental sap- 

 phire, the oriental amethyst, the 

 oriental topaz, and the oriental 

 emerald. Some varieties of sap- 

 phire exhibit particular kinds of 

 opalescence, and these have obtained 

 the name of girasol sapphire, cha- 

 toyant or opalescent sapphire, and 

 asteria or asteriated sapphire, the 

 last, when cut en cabochon, presents 

 a silvery star of six rays, in a 



