SI N 



SI P 



SILVAN. The name given bj' Werner 

 to the metal tellurium. 



SILVER. Argentum. A white metal 

 occurring often in the metallic state in 

 mines, and in combination with ores of 

 lead, from which it is separated by cupel- 

 lation. Horn silver is the chloride, re- 

 sembling horn in consistence. Fulmi- 

 nating silver is an explosive substance, 

 formed of oxide of silver and ammonia. 



SILVER GLANCE. Vitreous silver, or 

 sulphuret of silver; a mineral occurring 

 massive, crystallized, and in other ex- 

 ternal forms, among which are the lami- 

 nar and the capillary. The black silver 

 ore appears to be a pulverulent variety 

 of this species. 



SIMARUBACEiE. The Quassia tribe 

 of Dicotyledonous plants. Trees or 

 shrubs with leaves alternate ; flowers 

 polypetalous ; stamens twice as many as 

 the petals, hypogynous ; ovarium 4- or 5- 

 celled ; fruit, indehiscent drupes. 



SI'MIADiE {simia, an ape). A family 

 of Quadrumanous animals, including 

 the apes, monkeys, and baboons of the 

 Old World. 



SIMILAR FIGURES. In Geometry, 

 figures are termed similar, when they 

 resemble one another in shape, without 

 reference to their size ; when the latter 

 point of resemblance exists, the figures 

 are said to be equal. 



SI'MILOR. The designation of an 

 alloy of zinc and copper. 



SIMOON. An Arabic" term denoting 

 poison, and applied to a hot wind which 

 occurs in most countries situated near 

 sandy deserts, and blows from the quar- 

 ter of the desert. In Turkey the wind 

 is called Samieli ; in Egypt, Khamsin ; 

 in Guinea and Senegambia, Harmat- 

 tan. 



SIMPLE MINERAL. A term applied 

 to individual mineral substances, as dis- 

 tinguished from rocks, the latter being 

 usually an aggregation of simple mine- 

 rals. They are not simple in regard to 

 their nature ; for, when subjected to che- 

 mical analysis, they are found to consist 

 of a variety of different substances. Py- 

 rites is a simple mineral in the sense in 

 which we use the term, but it is a chemi- 

 cal compound of sulphur and iron. 



SINE and COSINE. In Trigono- 

 metry, the sine of any arc of a circle is 

 the straight line drawn from one ex- 

 tremity of the arc perpendicular to the 

 radius passing through the other extre- 

 mity. The cosine is the sine of the com- 

 plement of an angle or arc, the prefix 

 304 



CO being merely the abbreviation of com- 

 plement, first introduced by Gunter. 



SINGULAR TERM. A singular term, 

 in Logic, is that which stands for one 

 individual, and cannot, therefore, be 

 predicated affirmatively of any thing but 

 that individual. See Common Term. 



A Singular Proposition is one which 

 has for its subject either a singular term, 

 or a common term limited to one indi- 

 vidual by a singular sign, e. g. "This." 

 Such a proposition is universal, when the 

 whole of the subject is spoken of; parti- 

 cular, when only a part is spoken of, e. g. 

 " Non omnis moriar." 



SINTER {sintern, to drop). A Ger- 

 man name for a rock precipitated from 

 mineral waters. Calcareous sinter is car- 

 bonate of lime deposited in layers ; sili- 

 ceous sinter, a variety of common opal. 



1. Sinter, ceraunian. A variety of 

 quartz consisting of siliceous tubes 

 found in the sands of the Senner Heath 

 in the county of Lippe, where, on ac- 

 count of their supposed origin, they are 

 called lightning tubes, and hence are 

 derived the terms fulgurite, astraphya- 

 lite, &c. 



2. Sinter, quartz. Stalagmitic quartz, 

 the most remarkable varieties of which 

 are the siliceous concretions deposited 

 by the celebrated hot spring in Iceland, 

 the Geyser. Another variety is the pearl- 

 sinter from Santa-Fiora in Tuscany 

 (whence it has obtained the name of 

 fiorite), and from the island of Ischia. 



SINUATED {sinus, a bay or cavity). 

 Having a wavy margin, produced by 

 alternations of projecting lobes and in- 

 dentations. 



SIPHON {ai(pb)v, a tube). A hydraulic 

 instrument used for emptying liquids 

 from one vessel into another, without 

 disturbing the mass of the liquid. It is 

 merely a bent tube of which one leg is 

 longer than the other. When this is 

 filled with liquid, and the shorter leg 

 is immersed in a vessel to be emptied, 

 the atmospheric pressure on the surface 

 of the liquid will cause it to rise in the 

 shorter leg, and thus a continuous stream 

 will be produced. 



SIPHON (in Zoology). A sucker ; a 

 fieshy process, generally long, cylindrical, 

 and hollow, protruded by the carnivorous 

 and testaceous animals from the base or 

 channel of their shells. The same term 

 is applied to the slender shelly tube 

 which connects the chambers of cepha- 

 lopod shells, or the nautili. 



SIPHONO'STOMOUS iai<pwv, a tube, 



