497 



CAFFEIC ACID. 



CAIRN. 



the name given by ancient grammarians to the division of a verse into 

 two or more portions by a pause or pauses, the position of which must 

 be consistent both with the rhythm of the metre and the meaning of 

 the words. If in any metre the termination of every foot coincide 

 with the termination of a word, a painful monotony arises which 

 would soon offend the ear ; as in the lines, 



Sparsis liastis longis campus splendet et horret. Enn. 

 Disperge hostis, distrahe, diduc, divide, differ. Enn. 

 Has res ad te scriptas Luci misiinus Aeli. Lttcil. 



This has led some grammarians to hold the opinion that the several 

 feet of a verse should be blended together ; yet this principle might 

 U'ail to results no less offensive than the lines that have been just 

 quoted, as may be seen in the following verses : 



Sole cadintc juveneus aratra reliquit in arvo. 

 rioAAa J' avtarra. KOTOVTO Trapaira Tf $ox/u& ? i\\Bov. 



Much that has been written about the csesura betrays an inaccuracy 

 which has arisen from a neglect of the principle of accent. Those who 

 define verses by the mere order of the long and short syllables find it 

 necessary afterwards to lay down what appear to be arbitrary canons. 

 Thus a word of three long syllables, such as prorunipunt, might, accord- 

 ing to the usual definition of an hexameter verse, occupy any place 

 which did not interfere with the two short syllables of the fifth foot. 

 Yet an ear acquainted with the true rhythm of this verse would be 

 violently offended by any line beginning with R franmfmtt, ae Oat- 

 ,>/-<>riiinjiunt, or Continuo no&tri jam prorumpitnl ulidanfes. The 

 true objection to these lines is that the accent of the word prarampunt, 

 which of course falls upon the penult, is inconsistent with the demands 

 of the verge, which, in the positions here given to the word, would 

 compel us to falsify the accent, and pronounce pr6rump&nt, [HEXA- 

 METER.] A part of these difficulties they evade by adding to the 

 previous definition of the hexameter a canon to the effect that there 

 must always be a caesura at the end of two feet and a-half, or three 

 feet and a-half, with the additional proviso that the syllable imme- 

 diately preceding the cajsura must not be a monosyllable. To this 

 canon there are two serious objections besides its arbitrary character : 

 one that it does not exclude pn/rumpunl from its position in the third 

 example ; the other that it lays down a rule which is violated in many 

 of the finest verses of the jEneid. The same neglect of accents has led 

 to precisely the same difficulties in the other metres. 



The name of caesura or TO/ITJ (or itiupa, which has the same meaning) 

 i sometimes given to that portion of a verse which precedes the pause. 

 Thus when the pause occurs at the end of the fourth foot of the 

 hexameter, that fourth foot being a dactyl, which is common in the 

 bucolic writers, the four first feet so cut off bear the name of a bucolic 

 Ciesura. 



CAFFKIC ACID. [TAXNIC ACIDS.] 



CAFFEINE, mine, Ouaranine (C lr H IO N.0 4 + 2 Aq.). A crystal- 

 line alkaloid found in coffee, tea, and two other vegetable preparations, 

 namely, in guarana, a paste prepared from the seeds and other parts of 

 the Paulllnia surhilit, and in the leaves of Ilex Parar/uayemis, both of 

 which are used in the production of beverages in the Brazils and a few 

 other parts of the world. Caffeine was first discovered in coffee by 

 Kunge in 1820, and a few years afterwards in tea by Oudry, who called 

 it theine : the identity of the two substances lias since, however, 

 been fully established. 



It exists, according to Payen and other chemists, in combination 

 with potash and chlorogcnic, caffeic, or caffetannic acid, and is best 

 prepared as follows : A decoction of tea or coffee is mixed with excess 

 of solution of basic acetate of lead and filtered ; through the clear 

 liiiui'l is passed a current of sulphuretted hydrogen, the sulphide of 

 lead separated by filtration, and the filtrate evaporated to a small 

 bulk. On cooling the caffeine crystallises out nearly pure, and may 

 be rendered quite white by boiling in water or ether with a little 

 powdered animal charcoal, filtering and recrystallising. 



So obtained, it presents the appearance of long silky needles. They 

 in 81 i*r cent, of water, which is not thoroughly separated 

 bcluw a temperature of 302. At 352 they melt, and at a higher heat 

 sublime without decomposition. It is readily soluble in ether; also 

 in boiling alcohol or boiling water, but from these it nearly all 

 crystallises out on cooling. Heated with strong alkalies it is decom- 

 posed with production of methylamine. Hydrochloric acid dissolves 

 if. but on evaporation it is deposited unchanged. Caffeine, never- 

 theless, does possess basic properties, and, by carefully avoiding the 

 presence of water, several well defined salts may be obtained. The 

 most remarkable and beautiful of these are the double chloride* with 

 platinum, gold, and mercury. 



Caffeine is powerfully attacked by oxidising agents, giving rise to 



several bodies of considerable interest, inasmuch as they establish its 



intimate connection with the uric group of the formic series of organic 



compounds. These are : 1st, ;un:ilir acid, obtained by Rochleder on 



passing a current of chlorine through caffeine suspended in water, 



wj the caffeine is all dissolved, filtering and 



filtrate ; 2nd, Cholestophane (the nitro-theine of 



8tenhouse> ; obtained by the /<iW<;</<r/ action of chlorine or nitric 



acid; and 3rd, Murexoin, obtained by the action of ammonia on 



arnalic acid. These bodies are homologous with alloxantine, porobanto 



ARTS AXJJ SCI. I'tV, VOL. II. 



acid, and murexid (compounds obtained by similar processes from 

 uric acid), and differing only from these latter by having equivalents 

 of the radical methyl (C..H.,) in the place of an equal number of 

 equivalents of hydrogen. The following diagram will show this at a 

 glance : 



rarabanic acid 

 Dimethyl-parabc. 

 acid, or Chole- 



C 1 ,n 4 N 1 O l 



CjH.jN.,0,, 



Alloxantin . 

 Dimethyl-alloxan- j 

 tin, or amalic 

 acid . . ) strophaue 



Murexid ..... C 16 H 8 N O la 

 Dimethyl-murexid . . . . \ . . 

 Caffeo-murexid, or murcxoin . / L io 1 *l l 'a J1 3'*"o < -'i2 



The use of caffeine as an article of diet has not yet been satisfactorily 

 ascertained. That this is a question of no mean interest is obvious 

 when we consider that it exists in four substances differing widely 

 from each other in their botanical origin, and yet all instinctively used 

 for the same purpose by the various nations of the world, namely, the 

 production of useful and agreeable beverages. Liebig suggests that it 

 contributes to the formation of taurine, a compound peculiar to bile. 

 He considers bile to be one of the products of the decomposition of 

 animal tissues, and has lately found caffeine in muscular flesh. 

 Lehman has found that its administration is always followed by a 

 slight augmentation of the secretion of urea. 



CAFFEO-MUREXID. [CAFFEINE.] 



CAFFETANNIC ACID. [TANNIC ACIDS.] 



CAFFILA is the term used in Northern Africa for those companies 

 of travelling merchants which in Asia are called caravans. The order 

 in which they are arranged is the same, but the caffilas being generally 

 less numerous than the caravans, this order is not so strictly observed. 



CAIMACA'N, more properly Kaimakam, a Turkish name which 

 corresponds to our lieutenant, or rather lieutenant-governor. The 

 caimacan of Constantinople is the lieutenant of the grand vizir, 

 whom he represents in processions when absent. It is an office of 

 importance, and the person who fills it is generally styled pasha. 

 (La Croix, ' Me*moires sur 1'Empire Ottoman.') The pashas or 

 governors of provinces have also their caimacans or lieutenants, who 

 often act as governors of the principal towns. 



CAlNCIC ACID (C^H.,,0,, ?). This acid is obtained from the 

 root of the Chiococca anyuifuya, a plant employed in the Brazils as an 

 antidote for the bite of serpents. -It is also contained in the root of 

 the Uhiococca racemosa. The acid is extracted by digesting the 

 powdered root in alcohol, concentrating the alcoholic extract, then 

 adding water and filtering. The filtered liquor is treated with milk of 

 lime, by which an insoluble sub-caincate of lime is produced. This 

 salt is then to be decomposed by a hot alcoholic solution of oxalic 

 acid ; when, after filtration and cooling, the ca'incic acid is deposited in 

 the form of small needles. 



Camcic acid is inodorous, bitter to the taste, reddens litmus, dis- 

 solves in 600 parts of water, but is much more soluble in alcohol. 

 Acids and alkalies transform it into qainoratic acid and grape sugar. 

 Taken internally, ca'incic acid acts as a powerful diuretic. 



CAIRN, a heap of stones piled over the remains of the dead. Lhuyd, 

 in his ' Additions to Camden's Britannia in Radnorshire, asserts that in 

 the Cambro-Britannic Kaern is a primitive word, appropriated to 

 signify such heaps of stones. Cairns and tumuli of earth were the 

 common monuments which the ancient Britons, like the Northern 

 races generally, erected in honour of their great men, as indeed they 

 appear to have been of the most aboriginal races. [TUMULUS.] Which 

 of the two kinds was to be adopted was probably determined by the 

 circumstance of the country being stony or otherwise. 



Pennant, in his 'Voyage to the Hebrides,' 1772 (4to. Lond. 1790, 

 vol. ii. p. 208), speaking of the cairns, says, " These immense accumu- 

 lations of stones are the sepulchral protections of the heroes among the 

 ancient natives of our islands : the stone chests, the repositories of the 

 urns and ashes, are lodged in the earth beneath ; sometimes one, some- 

 times more, are found thus deposited ; and I have one instance of as 

 many as seventeen of these stone chests being discovered under the 

 same cairn. The learned have assigned other causes for these heaps of 

 stones ; have supposed them to have been, in times of inauguration, 

 the places where the chieftain-elect stood to show himself to the best 

 advantage to the people; or the place from whence judgment was 

 pronounced ; or to have been erected on the road-side in honour of 

 Mercury ; or to have been formed in memory of some solemn compact.' 

 (See Rowland's ' Moua Antiqua,' p. 50 ; Borlase's ' Antiq. of Cornwall,' 

 p. 209.) These opinions were once very prevalent, but it is now gene- 

 rally said that the cairn was simply monumental. 



" These piles," Pennant adds, " may be justly supposed to have been 

 proportioned in size to the rank of the person, or to his popularity : 

 the people of a whole district assembled to show their respect to the 

 deceased, and by an active honouring of his memory soon accumulated 

 heaps equal to those that astonish us at this time. But these honours 

 were not merely those of the day; a^ long as the memory of the 

 deceased existed, not a passenger went by without adding a stone to 

 the heap : they supposed it would be an honour to the dead, and 

 acceptable to his manes. To this moment," he continues, " there is a 

 proverbial expression among the highlanders allusive to the old practice : 

 a suppliant will tell lii* patron, 1'u.iTi mi clock er do clmnr (1 will ndcl 



