CKTYl.I'lsri.I'HUCAUIiONIC A i II'. 



CHAIN Kl'l.l-. 



711 



The soda tali, called nl*> '/// an>l tudium, u a yellowish- 



pay wlid. It uielU at 2\T Fahr., and at -J3U' Kahr. U a clear liquid. 

 Boiling water does not affect it ; hydrochloric acid decompose* it into 

 chloride of sodium and hydrate of cetyL When '//< of rrtjrf (pro- 

 duced by the reaction of iodine, phosphorus, and hydrate of cetyl) IH 

 heated with cetylate of mxla, at a temperature of 230 Fahr., aside of 

 rrty/ u obtained. 



arideo/edW(C^H M O t ) result*, iu the manner jut indicated, by 

 virtue of the following decomposition : 



Iodide of OtvUte Iodide of Oxide of 



cetTl. ufwda. odium. cetyU 



The iodide of s-xHuiii may be washed out with water, and Uie oxide 

 of oetyl jmrified by crystallisation from boiling alcohol or ether. It is 

 a very stable substance ; neither hydrochloric nor nitrohydrochloric 

 acid affect it It melts at about ISO* Fahr., and at 572 Fahr. di.-tils 

 without decomixMition. 



c H 1 



CUoridt of ftlyl, "f [. i " oily body, lighter thau water, 



derived from hydrate of cetyl by reaction with |rchloride of phos- 

 phorus. When chloride of cetyl is heated with an alcoholic solution of 

 monosulphide of potassium, ntyl-iulj>tiiidric filter, is produced, more 

 "imply called 



.v*ljMd< of nlyl (c.,HJS, = jj* } S,), purified by washing with 



water and crystallisation from a mixture of alcohol and ether. It in 

 obtained in spangles of considerable lustre. They melt at 135'5 Fahr., 

 and solidify into a radiate macs of crystals at 129-2 Fahr. 



Unlphydratt of cetyl (c^H^S, = ^'jj" | S,), or fctyl-tulfJiydric 



acid, or tetyl-mrrrajitaii. When alcoholic solutions of chloride of cetyl 

 and sulphydrate of potash are mixe<l, sulphydratc anil sulphide of cctyl 

 are produce<l ; the first is obtained pure by adding to the mixture 

 acetate of lead, washing the precipitate with water, and Dually digest- 

 ing it in ether, when it dissolves out, and may be crystallised by evapo- 

 ration. It melt* at 123 Fahr., and re-solidifies at about 111 Fahr. 

 In other respects it much resembles sulphide of cetyl. 



,ull>huric arid (C M H M O, HO, 2S0 3 ), (sulj./xx-ttic arid). At the 

 temperature of boiling water hydrate of cetyl combines with sulphuric 

 acid ; the mass dissolved in alcohol, and an alcoholic solution of pota-h 

 added, yields sulphate of potash, which precipitates, arid celyltalphate of 

 potaik (C M H < i. KI '. -SO,), which remains in solution; by evaporation 

 and reoiystallimtioii it is obtained in beautiful pearly plates. 



Cctyt-difulphocarbmic acid (C M H M 0, HO, 2CS t ). The potash silt c 'I 

 this acid, V C,,H M 0, KO, 2CSJ, is obtained by adding finely powdered 

 hydrate of potash to a saturated solution of hydrate of cetyl ill bisul- 

 phide of carbon. The glue-like product dissolved in alcohol yields on 

 evaporation flocks of rttyldituljthocarboaate of jiolath. The solution of 

 this salt precipitates salts of mercury, silver, lend, and rinc. Hydro- 

 chloric acid sets free hydrate of cetyl. 



Tri-tftytawioe, 



\ J 



. II 



obt-iiiicd by the action of 



auimoniacal gas on iodide of cetyl at a temperature of about 356 Fnhr. ; 

 iodide of auunouium precipitate* and the liquid |mrtion consists of the 

 above base. From solution in aleoh,.l this sulxtance crystallises in 

 colourless needles. Melting point. I".".'. It combines with acids to 

 form salts, all of which are insoluble in water, but soluble in alcohol 

 or ether. 



t, i< ',, 



f ( ' 1 ,H M 

 = NJC,,H,, 



produced by 



reacting with excess of aniline on iodide of cetyl. The iodid>- of 

 pheiiyl-anunoniuiii that result* at the same tune is removed by 

 washing with a mixture of ether and water, aiul the cetylaniline con- 

 verted into a bydrochlorote, which is decomposed with caustic potash 

 and crystallised from 1 toiling alcohol. Tim.- obtained, it occurs iu 

 plate* of considerable lustre. Melting |~.int, 1071; Kahr.; solidifying 

 point, 82'4* Fahr. It in insoluble in water, very soluble ill alcohol or 

 ether; it neither precipitates metallic -"lnti"in nor acts upon vegetable 

 colour*. It combine* with acids to form salts, most of wl. 

 crystal line. 



rc M H M 



'l n \ N< C,,H M ,i obtained by acting with one 



(.C,,H, 



equivalent of Iodide of cetyl on one equivalent of cetylaniline. It much 

 resembles the Utter lly. but i. mi< I'n-ilcl.-. 



CETYLDISfLPHOCARBONIC ACID. ICi.m I 



VI. |c ACID. [PALMITIC ACM,.] 



' llVAIilc A< 'ID, a iwculiarocid obtained by IVll.-ti.-r :m.l i'.iv.-n..ii 

 from ceradilla, the seed of tin- !'</'; ,/. .'/,<//'//<>. \Vhcn this seed 

 is dincted in ether, a fat oil, consisting of uteariin and elaine, in 

 dissolved; the nil, *eintted from the ether l.y distillation, i" then 

 mpuliinwl by potash ; this soap is dtcolnpoM-d by tartaric acid ; the 

 fat acids, set free, are separated by Uie filter; and the solution U-ing 

 distflkd, cevadic aci.l, mixr.1 with much water, is condetwcd in the 



receiver : this is saturated with baryta, and the salt obtained by 

 evaporation to dryness is mixed with phoph nd distilled. 



The oevadic acid sublimes in white pearly needles which fuse at 67 

 Fahr., and exhale the same smell as butyric acid, or as rancid butter, 

 which owes its smell to the latter acid. Cevadic acid sublimes at 

 a few degrees above its melting point, and it U soluble in water, 

 alcohol, and ether. Its salts are but little known, but they retain 

 the smell of the acid ; the salt of ammonia precipitates the pel-salts 

 of iron white. Cevadic acid is also probably contained in the root of 

 white hellebore and of i -ol< -Im-uni. Its composition is not known. 



cH.KlKH'in I.I. INK. An alkaloid of unknown composition, found 

 iu the grains of the Vlinrojilii/Uum Mliuemu. 



CHAIN CABLES. [OBoV.ND TACKLE.] 



CHAIN (in surveying) is a measuring chain of 10U links, alti 

 4 poles, or 66 feet, or 22 yards in length, so that ten square chains 

 make an acre. It U commonly called Gunter's chain, having been 

 first used by him, and described in his treatise on the cross-staff, *c., 

 in the following words : " We may measure the length and breadth 

 by chains, each chain being four perches in length, and divided into 

 a hundred links, then will the work be more eosie in arithmetic 

 as ten to the breadth in chains : so the length in chains to the content 

 in acres." 



The chain is of universal use in modern surveying ; but care inu-t 

 be taken to verify its length from time to time, since the material 

 is very extensible, and the apparatus must necessarily be roughly used. 

 It is stated in the account of Tronghton (Ast Soc. Monthly N 

 Feb. 1836), that the chain* of two surveyors, who differed in their 

 measurement, being sent to him, one was found two inches too short, 

 the other three inches too long. 



CHAIN RULE. Thk is a name given to u ride of arithmetic by 

 which when a succession of equivalents is given, the last of each 

 being of the same kind as the first of the next, a relation of equi- 

 valence is established between numbers of the first and lost kind men- 

 tioned. Thug, if three horses be worth -<\<n <>-. and ten cows be 

 worth thirty-nine sheep, and two sheep be worth fifty-three geese, it 

 can be found how many geese are worth, say eleven horses, or how- 

 many horses are worth a thousand geese. Sm h questions, and thr 

 mode still adopted of solving them, are found in the Hindu ' Lilivati,' 

 and in the earliest European books on arithmetic and algebra. They 

 invlve a chain of equivalents, each link of which is joined to the pre- 

 ceding and following one by the same names, and the first name of the 

 first link U the same as the second name of the last; whence the 

 name c/tain-ridc. The process applies with great practical u 

 questions iu the arbitration of exchanges. 



The process is nothing but that of composition of ratios; but it 

 may be simply exhibited thus : Let it be that 



3 horses arc worth 7 cows, 



10 cows ., 39 sheep, 



2 sheep 53 geese, 



How many geese 11 horses I 



From the first, 8x10 horses are worth 7 x 10 cows, which from the 

 second, are worth 7 + 39 sheep : hence 2x3x10 horses are worth 

 2 x 7 x 39 sheep or S3 x 7 x 39 geese. Hence 2x3x10x11 horses arc 

 worth 53 x 7 x 39 x 11 geese, or 11 horses are worth 53 x 7 x 39 x 11 

 -(- 2 x 3 x 10 geese. By such reasoning the following rule i 

 lilished : divide the product of the numbers in the column which ha 

 not vacancy by the product of the numbers in the column which haa :i 

 vacancy for the unknown quantity, and the quotient i the unmix i 

 with which the vacancy is to be filled up. 



It is obvious that any multiplier which cxi^t- in Ixith rolumiin in.", 

 be struck out )>efore commencing the process: this is tin- i 

 advantage of the rule, namely, that it ]*>ints out at once all the -impli 

 ficatious which can IK- introduced by division. 



The common rule of three, and \.uions other rules, may IK' brought, 

 under the chain-rule ; but an reduce 



under it every question the answri ' ,1 by dividing one 



product by another. This has liccn done in all - ih.it ot'th- 



I, ilivati to the present. ole, if seven men can reap 



acres in ten days, how long will it take thirteen men to te.ip m 



acres T The answer is found lonl.t by dividing 7 x 111 x in by 



13 x 8; but if we attempt to put these down in the chain form 

 have 



lo days 3 acres 



19 acres 13 



7 men f days. 



Now even if we grant that ten days are, iu the first clause, an 

 equivalent for (being the time oi reaping) tin <l that nine 



teen acres are in the second clause an equivalent f<u < i tin work of) 

 thirteen men : we still tiud it inqioHsiblc to make out in what sense 

 the seven men of the first clause are an equivalent to the unknown 

 number of day* in the second. But in truth the ten day in th. 

 lirst clause are not absolutely and indepeadantlj the time of doing the 

 three acres, but only mi condition that seven men are employed; 

 while in the second clause the thirteen men arc only the reapers of 

 nineteen acre* on the supjiosition of some one definite but unknoun 

 time being allowed. The question i* not therefore of the same class 

 as that which wo* first proposed, in which each quantity 



