n 



CHOLIC ACID. 



CHORD. 



Cboliunbus (x**Avi/&') is derived, which mean* lame iambus; the 

 metre limn, as it were, in the sixth foot. AnapovU appear in the 

 first foot, but in no other. Uipponax was one of the earliest writers 

 in choliambic verso, and has therefore been called the inventor of it. 

 The fragments of his poetry have been collected by Prof. Welcker. 

 Bunonion and Callimachus also wrote in this metre, and a few spe- 

 cimens from the Utter poet remain. The age succeeding the death 

 of Alexander contained many choliambic writers, who employed the 

 same antiquated dialect that they found in the compositions of Hip- 

 pooax and other*. The fable-writer, Babriua [BA.BRIUS, Bioo. Div.], 

 who lived a little before the Augustan age, revived the choliambic 

 poetry, and influenced probably by preceding poets, who hod adopted 

 the same metre, he appears not to have considered himself bound by 

 the custom of his own age in the choice of words. ('Philological 

 Museum,' vol. i.) 



CHOLIC ACID (C,,H NO lf ),(0Zy)eAo/i'<: arid; Glycochalalie acid). 

 Chobte of soda forms the principal portion of ox-bile. The cholic acjd 

 may be isolated and separated from the other biliary matters in the 

 following manner : Bile is evaporated to dryness, and dried at a tempe- 

 rature of 250* Fahr. The residue is digested in cold absolute alcohol, 

 the solution filtered, and ether added, which causes the separation of a 

 brown resin, after which crystalline tufts are gradually deposited. 

 These must be washed with absolute alcohol containing 10 per cent, of 

 ether, dried I'M racuo, redissolved in water, and dilute sulphuric acid 

 added. The solution slowly deposits crystals of cholic acid, which may 

 be further purified by another crystallisation from water. 



Cholic acid forms white acicular crystals ; they ore slightly soluble 

 in cold water, rather more so in boiling water. The solution has at 

 once a bitter and a sweet taste, and an acid action on litmus paper. 

 This acid is soluble in alcohol, lees BO in ether. 



When treated with alkalies, cholic acid is converted into cholalic 

 acid and ylycoci* (sugar of gelatin) : 



C.,H 1S NO,, + 2HO = C..H..O,. + C.H k NO. 



Cholic uid. 



Cholalic odd. Glycocin. 



Boiled with sulphuric or hydrochloric acids, cholic acid yields, first, 

 ckolonic acid ; then, gtycocin and chololdic acid ; and finally, liytlytin. 



Cholic acid combines with bases to form salts, some of which 

 are crystalline. With sugar and sulphuric acid it gives a purple 

 colouration. 



CHOLOIDANIC ACID (C^H^O,. f), one of the products obtained 

 by oxidising bile with nitric acid. It is most advantageously prepared 

 by boiling choldidic acid in a retort with moderately strong nitric acid 

 till no more red fumes are evolved. On cooling, a mass of crystals of 

 choldidanic acid separate out, which may be purified by pressure to 

 remove excess of nitric acid, and by recrystaUisation from boiling 

 water. They present the appearance of asbestos, are almost insoluble 

 in cold water, slightly so in hot water, and very soluble in alcohol. 



Choloidanic acid unites with bases, but the salts are with difficulty 

 obtained in a pure state. 



CHOLOIDIC ACID (C^H^O.!). Formed by boiling cholic acid, 

 choleic acid, or cholalic acid, with hydrochloric acid for three or four 

 hours. On the cooling of the solution, it separates out as a solid mass, 

 which may be purified by washing with water, solution in alcohol, and 

 evaporating to dryness. 



Cholbidio acid is a white solid, insoluble in water, soluble in alcohol, 

 and slightly so in ether. 



It decomposes carbonates with effervescence, but the salt* which it 

 forms are uncrystallisable. 



( IIOLONIC ACID(C M H 41 NO ), the body that is first formed on 

 boiling cholic acid with strong hydrochloric or sulphuric acids : 

 C.,H t ,NO,^= 2DO + C tt B tl KO lt 



Cholic add. Cholonic acid. 



It separates out in oily drops that solidify on cooling. It may be 

 purified by treating with caustic baryta, decomposing the resulting salt 

 with hydrochloric acid, and crystallising from alcohol. It forma 

 brilliant needles. 



Cholonic acid forms soluble salts with the alkalies. The soda com 

 pound is crystalline. With the alkaline earths it forms insoluble 

 combinations. 



The relation which the above-mentioned acids bear to each other, 

 and to bile, will be at once seen by a glance at the following table : 



CboMendd. 



Cholic a' Id. 



CbolMlftln. 



These acids are principally combined with soda, forming a species of 



The reactions with sugar and sulphuric acid, mentioned under 

 CHOLEIO and CHOLIC ACIDS, has been taken advantage of by Pettenkofer 

 as a means of testing for the presence of bile in organic matters. It is 

 best applied as follows : An extract, obtained by digesting the sub- 

 stance in alcohol and evaporating to dryness, is dissolved in a little 

 water, a few grains of sugar added, and pure sulphuric acid cautiously 

 poured in. A red colour ensues, changing to purple and violet if l>il<- 

 is present. [See also BILE, NAT. HIST. Div.] 



CHONDRIN. A kind of gelatine from which it differs in being 

 coagulated by vegetable acids. It is obtained by boiling the cornea of 

 the eye wrth water. 



CHORA'OUS, the name of a public officer at Athens. Each i>lnl>-. 

 or tribe, had a choragus (xopaybs), who was obliged to provide a 

 chorus to perform at the representations in the theatres, and at many 

 religious solemnities. The office was probably rotatory, though none 

 but rich persons able to bear the expenditure without inconvenience 

 could be forced to take it. (Fred. Aug. Wolf, ' Prolegomena in 

 Demosth. Orat. Leptin.' p. Ixxxvii.) The choragus had entire charge 

 of the whole choral apparatus : he paid for the dresses and the crowns, 

 and all other decorations. He also provided and paid a teacher 

 (XopoIiScbricaAof, chorus-teacher), who instructed and trained the 

 choristers in the arts and graces of their profession. Every expense of 

 whatever kind attendant on the equipment of a chorus, either in the 

 theatre or in any other exhibition, was discharged by the choragus. 

 The tribes vied with one another in the splendour of their exhibitions, 

 and especially hi the sumptuousness of the choral ornaments : some- 

 times the expenses incurred by the state were so heavy, that both the 

 treasury and the resources of individuals were exhausted. (See also 

 ' Xen. Hipparch.' i. 26.) In some cases the choragus seems to have led 

 the chorus in person, as well as to have defrayed the expenses ; and 

 once a choragus acted as flute-player at Sparta. (Hiiller, ' Dorians,' 

 voL ii., p. 841.) The term choragus included sometimes the gymnasi- 

 arch and the hestiator. (Fred. Aug. Wolf, in ' Demosth. Leptin. Orat. 

 Comment' 16, 24.) The former of these had. charge of the athletic 

 exercises of the youth ; and the latter was obliged to give a banquet to 

 his tribe on occasion of any great holiday or festival : these offices 

 were similar in kind to that of the choragus, which probably from 

 being the most expensive and important of the three, stands frequently 

 for the whole. The choragus is not to be confounded with the 

 choropoios (xoporoioj), who was general chorus-manager to all the 

 tribes. (Xenoph. ' Ages,' ii. 17 ; Miiller, ' Dorians,' voL ii., p. 841, n.) 

 Some age appears to have been fixed below which it was not com- 

 petent to a man to be made choragus : a choragus of boys could not t>r 

 under forty years of age ; the age required in other cases is not k n< > 1 1 . 

 A resident alien or metic (prrouos) could not hold the office. Demo- 

 sthenes was on one occasion a volunteer choragus, and was grievously 

 insulted during his term of office by Meidias. (Demosth. ' Against 

 Meidias.') A tripod was the common prize of the successful choragus, 

 who occasionally erected a small building on which he placed the 

 prize. Such is the beautiful choragic monument of Lysicrates (erected 

 about 334 B.C.) at Athens, vulgarly called the Lantern of Demosthenes. 

 These monuments were erected in the vicinity of the theatre, or in the 

 street on the eastern side of the Acropolis, which led from the Pry- 

 taueium to the sacred enclosure of Dionysus hence called the " street 

 of the tripods." 



CHOKD (in mathematics), a straight line drawn from one point to 

 another of a curve. [ARC.] The term chord was also used in trigo- 

 nometry, with sine, cosine, 4c., to denote the chord of a circle, in 

 which case it was also called the chord of the subtending angle. But 

 this term, not being wanted, has not passed into pure algebra with 

 sine, cosine, &c. [CIRCLE], so that when used, it must be considered as 

 retaining its primitive sense, namely, that of a straight line, not 

 an abstract number expressing the ratio of a straight line to the 

 radius. To find the chord of a given angle, multiply the diameter 

 by the sine of half the angle. Thus the angle being 23 20', and 

 its half 11 40', take the sine of the half, which is -2022176. If tlir 

 diameter be 100 feet, then the chord of 23 20' is 20'221 76, or 20J feet 

 nearly. 



To find the chord of a given arc, find the angle subtending the 

 given arc f ANUI.E], and proceed as before. The following Table 

 of Chords, to every degree up to 180, will frequently be useful 

 hi rough calculations. The diameter is throughout 10,000, to ,ivoil 

 decimals. 



TABU or CnoxiM (Duxcrn 10,000). 



