SUL 



SUR 



the radical sulphurous acid, combined 

 with amidogen. See Amides. 



SULPHATES and SULPHITES. The 

 former of these bodies are definite com- 

 pounds of sulphuric, the latter of sul- 

 phurous, acid with the salifiable bases. 



SULPHATOXYGEN. According to 

 the new view of compound radicals, this 

 body is the sulphate radical of sulphate 

 of soda, the oxygen of the soda being 

 referred to the acid ; its compounds are 

 termed sulphatoxide. 



SULPHO-SALTS. These are merely 

 double sulphurets, in the constitution of 

 which Berzelius has traced a close ana- 

 logy to salts. The sulphurets of the 

 most electro-positive metals have been 

 termed sulphur bases, whilst the sulphu- 

 rets of arsenic, antimony, &c. have been 

 called sulphur acids : the combination of 

 these bases and acids are sulphur salts. 



SULPHOVINIC ACID. (Enothionic 

 acid. An acid formed by the action of 

 sulphuric acid upon alcohol. 



SULPHUR. Brimstone. An elemen- 

 tary substance exhaled in large quan- 

 tities from volcanoes, either in a pure 

 state or in combination with hydrogen ; 

 by condensing in fissures it forms sul- 

 phur veins, from which the greater part 

 of the sulphur of commerce is derived. 

 It exists also in combination with metals, 

 and is extracted in considerable quantity 

 from bisulphuret of iron or iron pyrites. 

 It is likewise a constituent of sulphuric 

 acid in gypsum and other native sul- 

 phates. Lastly, it enters into organic 

 structures, being associated with albu- 

 men, in the fluid or the solid state. 



Crude Sulphur is the result of the dis- 

 tillation of native sulphur ; roll or stick 

 sulphur is sulphur which has been refined 

 and cast into wooden moulds ; flowers of 

 sulphur is the name given to sulphur 

 which has been sublimed, in the form 

 of a bright yellow powder. 



SULPHURET. A combination of sul- 

 phur with a base. A sulphuret is some- 

 times distinguished by the colour of the 

 compound, as the black and the red sul- 

 phuret of mercury. 



SULPHURIC ACID. An acid pro- 

 duced by the burning of sulphur, mixed 

 with nitrate of potash. It was formerly 

 called oil of vitriol, because it was dis- 

 tilled from a substance of mineral origin, 

 called vitriol on account of its imperfect 

 resemblance to green glass. This acid, 

 when obtained in the latter way, emits 

 white vapours on exposure to the air, 

 and is hence caX\%^ fuming sulphuric acid. 

 322 



SULPHUROUS ACID. A gas ob- 

 tained by burning sulphur in dry air or 

 in oxygen gas. By means of nitric acid, 

 the sulphurous is immediately converted 

 into sulphuric acid. 



SUN. The centre of the solar system, 

 and the dispenser of light and heat to 

 all the planets. Its distance from the 

 earth is computed at 95 millions of miles, 

 its diameter at 882,000 miles, and its 

 bulk is about thirteen hundred thousand 

 times greater than that of the earth. 



SUN-STONE. A yellow variety of 

 adularia, or naker felspar, with reddish 

 dots. This name is also sometimes given 

 to the beautiful avanturino variety of 

 common felspar. 



SUPERDOMINANT. The sixth of 

 the key, in the descending scale of Music. 

 The supertonic is the second above the 

 key-note. 



SUPERFICIES. Popularly, the sur- 

 face of any thing. In Geometry, it de- 

 notes the boundary of a solid, and relates 

 to the two dimensions of length and 

 breadth. The quantity of an area is 

 called its superficial content, as distin- 

 guished from linear content or length, 

 and from solid content or bulk. See 

 Surface. 



SUPERPOSITION. The process, in 

 Geometry, by which one magnitude may 

 be conceived to be placed upon another, 

 so as exactly to cover it, or so that every 

 part of each shall exactly coincide with 

 every part of the other. It is evident 

 that any magnitudes which admit of 

 superposition must be equal, or, rather, 

 this may be considered a« the definition 

 of equality. 



SU'PER-SALT. A compound of an 

 acid and a base, in which the acid is in 

 excess. See Sub-salt. 



SUPPLEMENT. In Trigonometry, 

 the supplement of an arc is its defect 

 from a semicircle ; the supplement of an 

 angle, its defect from two right angles, 

 or 180°. Also, chords or arcs of a circle 

 or other curve which have a common ex- 

 tremity, and together subtend an angle 

 of two right angles at the centre, are 

 sometimes called supplemental chords or 

 arcs. The supplemental versed sine, or 

 suversed sine is the difference between 

 the versed sine and the diameter. 



SUPRACRETACEOUS ROCKS. A 

 term applied by geologists to certain 

 rocks or strata which are situated above 

 the chalk. They are also termed ter- 

 tiary strata. 

 SURD. This term denotes, in Alge- 



