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T A L 



SY'NTHESIS. (avvOtvig, Gr. from avvri- 

 0t/jui, to join together ; synthese, Fr.) 

 The act of joining ; opposed to analysis. 

 Water is proved to consist of oxygen and 

 hydrogen by analysis, that is, by decom- 

 posing water and ascertaining its constitu- 

 ents ; it may however be proved to consist 

 of oxygen and hydrogen by synthesis, 

 that is, by uniting the relative proportions 

 of oxygen and hydrogen. 



SY'PHON. ) See Siphon and Siphun- 



SY'PHUNCLE. $ cle. 



SYRI'NGODENDRON. The name given by 

 Count Sternberg to many species of sigil- 

 laria, from the parallel pipe - shaped 

 flutings that extend from the top to the 

 bottom of their trunks. These trunks 

 are without joints, and many of them 

 attain the size of forest trees. Prof. 

 Buckland. Bridgewater Treatise. 



SYSTE'MIC CIRCULATION. The circulation 



of the blood through the body generally, 

 as distinguished from that other circula- 

 tion which is confined to the respiratory 

 organs and the heart, or the respiratory 

 circulation. 



SY'STOLE. ((rvoroXr), Gr. contraction, 

 systole, Fr.) A term used to signify the 

 heart's contraction. The two movements 

 of the heart are its systole and diastole ; 

 by the systole of the heart, or its contrac- 

 tion, the blood is pressed out of the heart 

 and forced into the arteries ; by its dias- 

 tole, the blood is received from the veins 

 into the heart. 



SY'ZIGY. (from (rv^vyia, Gr. conjunction; 

 syzygie, Fr. ) A term applied to the con- 

 junction or opposition of a planet with the 

 sun. The syzygies of the sun and moon 

 occur at the time of full and new moon ; 

 the tides are much increased, and are 

 called spring tides, in the syzygies. 



TABASHEE'R. A siliceous concretion found 

 in the joints of the bamboo : by some it 

 has been supposed to be the juice of the 

 plant inspissated and hardened. It is 

 remarkable on account of its peculiar 

 optical properties ; its refractive power is 

 between air and water, namely 1-111. 

 The finest varieties reflect a delicate azure 

 colour, and transmit a straw-yellow tint, 

 which is complementary to the azure. 

 When it is wetted slightly with a wet 

 needle or pin, the wet spot instantly be- 

 comes milk-white and opaque. The appli- 

 cation of a larger quantity of water re- 

 stores its transparency. The word is 

 from the Persian. Dr. Brewster. 



TA'BULAR. (from tabularis, Lat.) Formed 

 in laminae or plates ; having a flat or 

 square surface ; in large plates. 



TA'BULAR STRU'CTURE. This.form of struc- 

 ture consists of parallel plates, separated 

 by regular seams ; it is the consequence 

 of crystallization, and though closely allied 

 to the columnar structure, is not uncom- 

 monly confounded with stratification. 

 Mr. Bakewell. 



TA'BULAR SPAR. The schaalstein of Wer- 

 ner ; spath en tables of Haiiy ; prismati- 

 scher augit-spath of Mohs. A greyish- 

 white mineral, occurring massive and in 

 granular concretions. Lustre' pearly ; 

 fracture splintery; translucent. Specific 

 gravity 2- 7 to 3*2. Its constituents are 

 silica 51-40, lime 45-0, oxide of iron a 

 trace, water 4'0. It occurs in primary 

 rocks in Norway and other places. 

 TA'BULATED. (from tabula, a table, Lat.) 

 Having a flat surface. 



TALC. ) (talk, Germ, talc, Fr.) A some- 



TALCK. $ what fibrous and very commonly 

 foliated mineral, resembling mica in its 

 lamellar structure, but its laminae not 

 being elastic as are those of mica. Its 

 colours are white, pale yellow, or greenish. 

 Both its surface and powder are unctuous 

 to the touch. It is so soft as to be easily 

 scratched with the finger-nail. Its lustre 

 is often pearly, or inclined to metallic. 

 It is translucent, and, when divided into 

 thin laminae, transparent. Specific gravity 

 from 2-58 to 2*90. Before the blow-pipe 

 it whitens, its laminae separate, and their 

 extremities fuse into a white enamel. Its 

 constituents are principally silex and 

 magnesia, with small quantities of potash, 

 alumine, oxide of iron, and water. Talc 

 and chlorite are nearly allied, and pass 

 by insensible gradations, into each other. 

 Talc is sometimes used as a substitute for 

 glass, and windows are formed of its 

 laminae, which are sometimes obtained of 

 the size of twelve inches square. There 

 are two varieties of talc, namely, fibrous 

 talc and indurated talc. 



TA'LCITE. The nacrite of Brongniart ; talc 

 granuleux of Haiiy ; erdiger talc of Wer- 

 ner. A rare mineral, occurring in coats 

 or reniform masses, composed of very 

 minute shining spangles or scales. The 

 French have given to it the name of na- 

 crite in consequence of its pearly lustre. 

 When rubbed between the fingers, it leaves 

 a pearly gloss. For its constituents and 

 other particulars, see Nacrite. 



TA'LCOUS. ) Resembling talc ; containing 



TA'LCY. ( talc. 



