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VOL. , 11' Such Mofciarlca : property; of cja as eie !;V , thetfissu -'. ? lias becnweta M'i applietl ; to;1irlck ittehntikr Us tfi:f ' 3ri9intiu aW settles idownf often $6ru it frm the hoijse bro produce used inIasterin, schmorta vv; ,v 2. A.' cement thai contains much clay. ;7J neyfyacneatyx ' hardness; With this ingredient" itiwili Indeed be more plaHc and easier to work; and will make a smoother wall than mere -'. - : lime and sand ; but for al 1 the purposes of awallof vwhichi s strength must be admitted to: be? most ' be far V inferior to one) composed of those ingredients simply; In ad(li-J tibn to our own observations, we have the autlioiity i bf; Smeur onj the famous Eiigtneeiy for asserting, that f mortar of the : best iqtmlity ?Wheri inixec V - REMARKS OV THE PEEPARlTIOIST OF MORt ab J Carolina Pnfetsor of Chemistry und Mineralogy in the Uniyerkity bj fPiiblished by ordef the Agricultural Society of this State- . r Presuming that the .objects of this Society :ax0 sufficiently comprehensive to embrace all subjects appertaining to Rural . Economy, I take the liberty to offer a few remarks on the pre paration of, Lime7Mortalt, for buildingJ I have: been led to make choice of this subiect; from the belief that the defective ' and nenshable modes ofibuildihe:, common in many parts of our country, are owing, in ho small degree, to the imperfections of the mortar employed. The correctness 01 most 01 tue remarKS that will be offered on the composition of mortaiy I have had opportunity vto verify by actual experiment. 1 q some members of the Society,' particularly those who have been much conver sant with building, I must apologize for reciting f'ctsrand giv ing reasbn-s, already familiar to them. The explanations are made as plain als possible, for the sake of those who have not had opportunity to acquire the ame information. If any im provements can be suggested in tlie ordinary moiles of making mortar, it is doubtless important that they should be generally known ; for it is only .in the most expensive undertakings, ,and " consequently in such as are" of rare occurrence, that we can avail ourselves of the skill and experience of the professed ar- cbitcct. .-. - - i:-- The ancient Romans, who displayed tlieir political wisdom in so many ways, regarded the preparation of mortar of such vast importance to the strength of their architectural works, and the durability of those structures which they-designed for conveying to distant posterity an impression of their? opulence and power, that they enacted laws to prohibit the use of bad, and to enforce 'the" Use of good mortar. Nor, as we shall scc by and by, were their artisans less attentive to the subject than their legislators. And what-has been the consequence ? Such parts of their buildings, imd other public works, as tlie despoil ing hand of barbarians has spared, have only grown firmer and i more lmpensuaiue oy me lapse oi4 iwo mousanu ycara. ine mortar with which their structures of stone or marble were ce mented, has acquired a hardness which, in manyjeases, surpas ses that of the materials themselves, so that the whole fabric has gained the firmness 'of a solid rock. Happily, Roman Au thors have given us the exact details of the process by which this cement was prepared ; but neither their statement, nor the examination of the article as it is found in the remnants of their works, indicates that any thing was used in its composition but lime and sand : its excellence must therefore have arisen from the quality of these materials,' and the perfect' manner iri which they were united; . ; ; I propose to speak' of the chemical principles involved in the manufacture of quicklime, and the hardening of mortar ; of the qualities of good mortar; of its composition or formation $ and, finally, of the preparation of hydraulic mortar, or water cement. I. For the. sake of some who may not have hal opportunity to understaud the nature of the changes that ocur in the ma nufacture of quicklime, and the hardening of mortar, I'm ay be pennitted to explain the PiiiNciJpiEs on which these changes are produced.' ; . V 1 -Limestone, before it is burnt, is a compound of quicklime and fixed air, or what is called by cliemists carbonic acid. Some, who have never turned their attenticm to subjects" df this knd, may find it difficult to conceive, how a species of air can make a constituent part of' a body sq solid as limestone. This diffi culty, will vanish when they" reflcct,r that air consists of solid particles in a very .minute state of division ; that when it goes into union with a xsol id substance, as quicklime, those particles that were before separated in the form of air, are brought, by tin; force of attraction, so near to each other, as to be reduced into a, comparatively small space. On the application oflieat, tliese particles are expanded again to their former dimensions, and fly off from the solid Jn the state of.air. These principles enable us to explain what takes place in the conversion of lime- iiia titfT' ..I.l.l! Ti 1 ? a ' 'jl' 1 oiunt. 4uiu 4uiuiviiine. uy caicinauon, uie nxeu air, wnicn made' up forty parts in a hundred of the whole mass, is expellr its still retaining a portion of fixed air, the substance being partly in the stateof limestone, and Dartlv in tlia statftnfnmrk- lime On ihe other band, when the heat , is carried too high, ..v .iiMv, w-vuujCT paruaji vimncu, uy wnicn means lis quali fies are very mucli impau-ed rure limestones are not so much inclined to vitrify as thbseCwhich contain fbi-eien inc-redients. tuch as sand, clay or iron. Limestone containing either of ujcsc suustancesrcquires to be burnt with a lower heat, and continued longer than usual. When properly burnt, they often constitute some of; the best kinds-of lime, especially for water Will CM U - . ' ' ' . i ' . -Every 0116 knows that the properties of lime are greatl;al teredj byjcalcinatibn T"? only poipt upon hich ,it may be necessary to' remark; is the strong attraction quicklime has for the fixed air thatf enti rely open Jjo the' atmpsphereV i t wil 1 speedily acqui rearly the whole of what it had lost, and become; as unfit for mortar as powdered limestone would be ; and its strength is weakened, and its bronerties are! imnairetl, in proportion to the quantity t of this principle absorbed. JJence inikeeping lime, and in the i several operations attending? the manufacture of mortar we ought tb use all possible meaiis,to prevent its combining with f fixed air; I Some of these eans, will he! noticed as w& proceed. In j&reat-Britaih, it is deemed point of f so much importance to have the lime, when it is used, ; perfectly f free from carbonic acid, or fixed: air, that in the structure of tlie public works, at Woolwich, it Li taken hot from thp kiln, and used immediately .aftcrwaids. But after the mortar is made up, and applied to the purposes, for which it was intended then we no lbnger wish to prevent the lime from absorbing fixed air ; for oy this means, " arid by consolidating a portion of water, it returns from the state of quicklime to that of limestone, and resumes tlie hard ness it originally possessed whileih the state of massive rocl i Tlie hardening o, mortar, therefore, depends icliieflyfoii "two properties-tlie power of 1 absorbing ;fixed air from the atmos- ; phere; and of rendering solid a portion of waterr Slow drying ai$o coniriouies ycry mucn 10 us umuiuie iiaixiiicKS), tnu uuiu is necessary to enable it to acquire its greatest solidity. The unrivalled hardness of the Roman cement j is owing in part, no ! doubt, to the length of time that has been occupied in its conso lidation. - i;! i.; ; " -:! .' '.: .. II. The q,uaiities of good mortar a rc, " to adhere rea dily to the substances to which' it Is' applied ; to cement them together; and to acquire by time a strong hardness;" Conse quentiy, nortar win noi oe gooa h it cracK in urying, or u u - J WjtonlyVsmall portion' Jiarclnejjs aud dryness whichit spdil hayettaihed. C becomeis a uscfol Constituent w .yi'ui , uic aiiru tityi muse , w uu 11 y vy iieni -IV. JS y fry ' uiniru IP I is laid with good cement, the detached parts, after some; time, become united into one mass ;: so that the whole structure has the same firmness as it would have, were it composed of a sin gle mass of brick or stone; and a wall plastered skilfully, will present a surface almost as firmand impenetrable as marble.. On the contrary, it lis obvious that a cement which does not bind the detached parts of a structure together, operates merely would render the task neither arduous nor exjnsive. Next, to the materials for mortar, we were to considerV. 2. The vrovortion of tlie ingredients. For brick work. !the ' proportion generally recommended, is 1 -5 1 ime, ' or 4 , bushels ot -sand to 1 of lime Rut in a country likethis of which - lime is very dear on account of the distance to which f it is transported, the fact ought to be more cenerallv, known ? be soft and brittle when dry. When a chimney, I for instance, Hhm a good mortar may of lime. With clean sharp sand, one-tenth of good stbue liradi ' will answer very well and indeed, with proper management ; will compose a cement extremely hard. Masons complain; however, of its being too slwrt j. Jbut this -dihcultyjnay be bbvi- ! atedj,:. fi rst, by dexterity . i n the lise of phe';tr(iwelf f ? Jtityh v which may be speedily acquire secpndlyi liy siifieHhg (thb ; mortar to remain some time before it is used j and, thirdlV br r' irporati ne the materials very thor0uj2:hly td frethcr, especially; " n I i by fill mc: up tlie crevices, while the fabric has little .more sta- Kinct oiiuy, uiaii wiiat rersuus iroui piling ui ii k ur siuncs uuc upuu jusi ot'iure using. jh tins huujcci, ( i u'leoTiie ioiioying another. A wall likewise made of soft or rotten; mortarl will riihent. A cask of good stbile limei "which slacked with' great ; . I may be pardoned for" digressing here a little fronv the main subject, to give j?ome rules which will enable any.one to decide, whether a eiven mineral kinds are exceedingly various in appearance, buti may all be known by one or ; more simple trials. Limestone is generally of such a degree ofJhardncss as to'be readily scratched witlia knife ; but it is too hard to l)e, cut like soapstone -andgypsum. Jf a xlrop of any strong acid fall on limestone, it iwili boiLor effervesce.; This.is'the most convenient test, and is not apt to lead into error. - . Fprthe acid, oil of vitriol, or aqiia fortis, or ".undue aciu, may be employed, one or all of which mat gene- be be liable to cleave off oh every agitation, or even by its own weight ; or if it cracks, tlie aggregate strength of the wall will be feeble, compared! with that which would result from the firm cohesion of all its parts Let us enquirei then, by what means we may compose a jcement, which shall possess all the! good properties enumerated, without the bad. v HI. What relates to the composition or mortar, compre hends the selection of the matci ials the proportions iiv, which they are united -and the mode of incorporating them. J i. Materials. The essential ingredients of good mortar, it is well known, are lime and sand. But it is plain, that articles very diverse in kind f and ; quality may be signified by j these terms ; and it may be useful to enquire what ;kind of lime, and what kind of sand,1 are to be selected. ! It is asserted by I high authority, that the colcmred varieties of lime, the blue, for in-' stance, compose a stronger cement than the white. . The latter, ; indeed, consists more exclusively of lime, the foriner being mix-'.j ed with more or less iron, sand, or clay. These foreign iingre-! dicnts, however, improve the quality of the' mortar ; but Since i the white lime will take: a 'larger quaiiti ty - of sand, it is gene-1 raljy preferred in oiu market. An opinion may be; formed of) uie comparauve excellence oi a given specimen wuiie inue, by" observing the foree with which it slacks." 'Dip agnail mass into water, holding it with a pairtf tongs, and after it has re mained a sliort time, lay it upon a board. If it swells, cracks, and falls into powder, with great heat, we may pronounce it to be of good quality. If it does not slack readily, with the foregoing appearances, we may infer that it has much fixed air, which it has either absorbed since its calcination, or which was never entirely separated from it duiing that process. We may be sure the latter is the. case, when hard lumps remain after slacking. This preliminary experiment is a useful one, to ena ble us to judge of the.strength of bur lime, and tol regulate the proportion of sand accordingly. The best . way where it is practicable, I is to use lime recently from the kiln, or to burn Vit over just before it is used. In the election of the sand9 there is room for much care artd discrimination. : In all cases it should be sh arp and clean, perfectly free from clay or di rt. For brick work, coarse sand is preferable, because it makes the hardest cement; fb plastering, finer sand is better because it makes the compound more plastic. Such saud as is found on the banks of rivers, or iii tlie street, br at the bottom of hills Washed by rains, is the; kind intended. : Sea sand ' contains a ; mixture of certain' salts, which prevent mortar that is made With it from lardening, and therctore, when used, ought to be repeatedly washed with fresh WaterV v: In places, also, where sandvcanhot be touna tree trom clay or dirt, it may oe separated, trom tnese ingredients by washing. ; Ah appropriate apparatus has been contrived fortthis purpose and Various : expedients; may be de4 vised to suit different circumstances. In comr iffcrent circumstances. V In common operations, it w ill be suliicient to stir up the impure sand in a tub oi water : the saiid Jwjll first settle tp the bottom,-While;theotlier ingre dients rerriain suspended, and may be turned 'off along w waterl i If tliis be tirned Intoaparate viessel the impurities will, In time, fall to the boitom,' and. the same - wafer may be usedrepeatdlyirf vnlf ia fliA mnfir nf motiir'iAP Ji moontia -In ''-.'4l5ei .niiif tvr tothfJ T tarom?downth6. acid upon it, and then applied add certain portion of clay to their mortar or aflea to le liirrl1161 If effervesces, Iwe may cancIuHe it to be lect su'chsarid as; naturally a hlnrL-cru c" . j.mmj.u, uc jiu uiiu. vii?w in, renucr ine couinounu more piasuo; or in onerwonis thU mn-r i i8 aVd kept at a high heator an hour,- If to prevent Jts bein;of Bui iiny ajrhesw-e "th ft ' ? application ot water, we - great injuryto the ent byimpkr lit at, and crumbled into a tine powder, without Jumps or other' impiiriiies, was inixeu, iinmeuuueiy airer siacKing, Willi coarse sand that was sharp and clear in the proportion; of one to nine he lime forming one-tenthV of the whole, t mall beds jyero mad up at i timcih, order tl effectually incorporated. As little water is mssible'Was added,. j but the mass was rendered plastic c j a hoe. I As last as the beds werm sively thrown -into.a pit clug in the ground three.feet deejp, and. buuji iciitiy uujJtiL-iuua iu uuuictiu yiiuiu. . x1 1 ii any, me inur- tar was covered over with boards, ;aho suffered to iemain ;for three months. At tlie end, of this time it was taken uj wbrjd f over anew, and used for faying bricks. After ah interval bf. ) 5 j months since it was applied, 1'. have an. oppbrtunityjbf ' ctith ' pari tig it with suchlas Contained pne- lime matlej up in the ordinary wayand; used son it harder than either of those. I have detailed this experiment 7 with some minutebess,:hbping th vhb re engad in building, is d'ar, to know .how, small a p be biadc to answjsr the purpos ;wan induced to ; employ pure lime and sand, instead orclay or, dirt.-: It is pro- ! bablc, indeed, that anient might be mad r ions, that would answer tolerably well for, brick or: stone work j with(mt taking so much -pain it was mv blnprt to rnflko thfr hpsft r.metit nnsuihlR with ihb pntt I limp, it mav not he amiss to review thft aevernl VtjnVl'inuViw1fti:,f.--''-'i to see how eacli part of tlie process conduced jtb;my purpose ' I vi. he mortar t was madethre itfwa , ; : wanted for use, for two reasons : ; orie was, that the lime was oik . . hand if suffered to remain in the cask, its stength would be impaired by combining with more or less of fiXcdairrhe ' other reason v thatthe qualirof proved by keeping before it. is applied. 1 Ve are assured by orio, : Of the best authorities, on this subject, that such' mortar f-.4. not oiiiysets sooner, but acquires arter degiWof hard ness and : is less aptto rack I ab morjarw were proliibif eli rby$& i th'ahicfc'w-1ess:thaW-thi x.. iviy. ooieci oeiuff, uiniuuuui, u urcyeni uie aDSorpuon Oi ... fixedair the-reiasbn for - slacking mallarceM at aiime) janci stowing away the mortar as fast as it could: be made up,is suf ' fiently 'obviousa-v4i ; i 3. That aIfttleater pos ; V the mass should be rendeined plastic bWaraa,' is strongly re 7 v commended oy experienced masons. The Greekswe are toldy , :r ; deemed this noint so important- .that iii' the structure lot theit : lar buildings thjse parcels; f cqptained I in separate : oasons ' an d kept ten men Vat each ; jand , the precept of ancient masons td tbeir lab ihd tli shovl0ei their mortar wiiKKe STveat ty Hhm jtrow,i Thb Romans also are known ' to .liavebeateb their mortar with heavy machinery. Krhabs the principal ityisori for usih but! little water, is the greater probahility iniliis case pt; the ci)ni- k '1 pound Ibeingworkedihore eSectuaJ :t& jr'ii S.-xneiui ? Cause this turnisnea a con vcnient receptacie tor it,f ana partly. becausevl in thisSituation it vvaVscreerieS fromlhe action ot the rf f viuwiium iuiuci ii very wc, cAucpi. mm un-rjura ASlonpUl, r:T. Kees Cyclop: Attf'ljcrtap;? ; Vw
The Weekly Raleigh Register (Raleigh, N.C.)
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March 15, 1822, edition 1
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