CHO 



CHR 



CHLORIMETRY. The process of esti- 

 mating tlie bleaching power of chloride 

 of lime, by the quantity of a solution 

 of sulphate of indigo which a known 

 weight of chloride can discolour or render 

 yellow. 



CHLORINE (xXwpof, green). A green- 

 ish gas, obtained by the action of mu- 

 riatic acid on peroxide of manganese. It 

 was first described under the name of 

 dephlogisticated marine acid, and was 

 afterwards called oxy-muriatic acid. Its 

 compounds, which are not acid, are called 

 chlorides (or chlorurets), and are charac- 

 terized by the same prefixes as the oxides. 

 CHLORITE (xXopor, green). A fri- 

 able mineral, of a green colour, allied in 

 characters to talc and mica. It occurs dis- 

 persed in rocks, or forms beds of itself. 

 The species are chlorite earth, common 

 chlorite, chlorite slate, and foliated chlo- 

 rite. 



CHLORI'TIC SAND (xXwpop, green). 

 Sand coloured green by an admixture of 

 the simple mineral chlorite. 



CHLOROCARBONIC ACID GAS. An 

 acid termed by Davy phosgene gas, con- 

 sisting of chlorine and carbonic acid. 



CHLO'ROPAL. A silicate of iron, a 

 mineral found associated with copal ; its 

 varieties are the conchoidal and the 

 earthy. 



CHLO'ROPHANE (x^wpof, green, 

 (f)aiv(a, to shine). A variety of fluor spar, 

 which gives out an emerald green light 

 by the mere heat of the hand. 



CHLOROPHCE'ITE. A green mineral 

 found imbedded in basalt or in black in- 

 durated ironstone. 



CHLO'ROPHYLLE (xXwpof, green, 

 (piiWov, a leaf). The green colouring 

 matter of leaves. See Chromule. 



CHLOROUS POLE. A term founded 

 on the theory that the particles of matter 

 are susceptible of polarity. Hence that 

 pole of a particle of zinc or of hydro- 

 chloric acid, which has the attraction or 

 affinity which is characteristic of chlo- 

 rine, or chlorous attraction, is called the 

 chlorous pole. See Zincous pole. 



CHOKE DAMP. The name given by 

 miners to carbonic acid gas, which is apt 

 to be formed and to accumulate in coal- 

 mines. 



CHO'NDROPTERY'GII (x6v3pof, car- 

 tilage, TTTepv^, a fin). Cartilaginous fishes ; 

 one of the primary divisions of the class 

 Pisces, so named from their skeleton con- 

 taining little calcareous matter, and this 

 disposed, not in fibres or plates, as in Osse- 

 ous fishes, but in small granules. There 

 76 



are two orders of these fishes, viz. those 

 vfith free gills, as the sturgeons, and those 

 with fixed gills, in which the external 

 edge of the gills is attached to the skin, 

 as the sharks, rays, and lampreys. 



CHORD OF AN ARC {chorda arcHs, 

 the string of a bow). The straight line 

 which joins the two extremities of a curve 

 or arc. To find the chord of a given arc, 

 find the angle subtending the arc ; then, to 

 find the chord of the angle, multiply the 

 diameter by the sine of half the angle. 



CHORD IN MUSIC. A combination 

 of three or more harmonious sounds. 

 1. The perfect chord consists of any given 

 note combined with a major 3'* and a 

 perfect 5'^ ; this and its inversions are 

 called consonant chords. 2, The chord of 

 the seventh, or dominant seventh, con- 

 sists of any given note, combined with a 

 major 3"*, a perfect 5*, and a minor 7* ; 

 this and its inversions are called diS' 

 sonant chords. 



CHOROGRAPHY (x^pa, a country, 

 ypacpw, to describe). The description of 

 countries ; a term differing from geo- 

 graphy, as a part differs from the whole. 

 CHREMATFSTICS {xp^nara, wealth). 

 The name given by continental writers to 

 that branch of political economy which 

 relates to the wealth of nations. 



CHROMA'TIC SCALE (xpS^a, co- 

 lour). The scale of semitones employed 

 in music. The term chromatic either 

 denotes that the musical characters were 

 written in colours, or suggests the variety 

 of shades which, figuratively, charac- 

 terize this scale. By chromatic music is 

 usually meant that in which extreme 

 intervals are used. 



CHROMATICS ixpi^^fia, colour). That 

 branch of optics which treats of the 

 colours of light, their several properties, 

 and the laws by which they are sepa- 

 rated. 



CHROME ALUM. A term applied 

 to a crystallizable double salt, consisting 

 of sulphate of chromium. This salt is 

 isomorphous with alum, and analogous 

 to it in constitution, but the alumina is 

 replaced by oxide of chromium. 



CHROME IRON. Chromate of iron ; 

 one of the ores containing chromium; 

 it occurs massive and crystallized. 



CHROME YELLOW. A well-known 

 pigment, consisting of chromate of lead. 



CHRO'MIUM (xp^fxa, colour). A 

 metal found in a Siberian mineral, called 

 chromate of lead, or red lead, and named 

 from its remarkable tendency to form 

 coloured compounds. It combines with 



