CEM

134

CEM

i l

that hot climate is considerable, the cement is kept in a properdegree of softness by the alternate addition of small quantitiesof water and oil. The cement, being completed, is applied inthe usual manner, and speedily acquires a stony hardness.

The term maltha is also applied to a variety of bitumenor mineral pitch of a viscid and tenacious character; unctuousto the touch, and exhaling a bituminous odour. This sub-stance, as also Asphalte, (see Aspiialte ), has been success-fully used as a cement.

The celebrated chunam, of India , is a species of malthawhich has been used in that country from time immemorial.The method in which it is prepared at Madras is as follows:—

Take fifteen bushels of pit-sand, and fifteen bushels ofstone-lime; slack the latter with water, and when it hasfallen to powder, mix the two ingredients together, and letthem remain for three days untouched. Dissolve 20 lbs. ofmolasses in water, and boil a peck of gramm, (a kind of pea),and a peck of mirabolans to a jelly; mix the three liquors,and incorporate part of the mixture very accurately with thelime and sand, so as to make a very fluid cement; some shorttow is then to be beaten well into it, and it will be fit for use.The bricks are to be bedded in as thin a layer as possible of thismortar; and when the workmen leave off, though but for anhour, the part where they recommence working is to be wellmoistened with some of the above liquor before the appli-cation of fresh mortar. When this composition is used forstucco, the whites of four eggs, and four ounces of butter-milk, are to he mixed up with every half bushel of cement,and the composition is to be immediately applied.

Mastic is an external composition possessing peculiar pro-perties, which, in some cases, render it superior to Romancement, having the power of resisting heat and adhering toiron, copper, and even glass, with equal tenacity. It isgenerally applied to the exteriors of mansions, but it mayalso be very beneficially used for laying the floors of halls,kitchens, &c.

Mastic was first introduced from France by Hamlin, hutis now sold only by Messrs. Francis and White, at NineElms. It is composed of pounded stone, silver sand, litharge,and red lead, and, when manufactured, has the appearance ofvery fine sand. The manner of working Mastic is entirelydifferent from that of Roman cement.

To one cwt. of Mastic add one gallon of linseed-oil, and letthem be well incorporated by the labourer, which must heeffected by treading them together with the feet until theamalgamation is complete, which may be easily ascertained bysmoothing a portion of the mixture with the shovel: shouldany bright spots be observable, the treading must be againand again repeated until they completely disappear, when itis considered fit for use.

The manner in which Mastic is used is as follows:—Thejoints of the brickwork being well cleaned out, the workmust be correctly plumbed up by means of flat-headed nails,and screeds, for the guidance of the floating-rule, formed withRoman cement, and kept about one inch in breadth. Thisbeing done, the bricks must be well saturated with boiled lin-seed-oil of the best quality, and the Mastic laid on with thehands, assisted occasionally by the laying-trowel, until thespace between the screeds be covered to the thicknessrequired. The floating-rule is then passed carefully overthe work; and when the space between the screeds is suffi-ciently filled up, it must be floated with a hand-float, com-posed of sycamore or beech, until it assumes the sameappearance as highly-polished stone. Thus a space of largedimensions must be followed up until the whole is completed,when the screeds must be cut out, their places filled withMastic , and compactly hand-floated into the rest of the work.

Within the last few years various compositions have heedinvented for the covering of the exteriors of buildings, su c ^as Roman Cement, Terra Cotta , Bailey’s Composition, andhost of others, all more or less patronized by the public. ^It would be impossible for us to give descriptionsall these compositions; but we shall shortly explain 1mode of preparing and using the Homan cement. This ceme >familiarly known among plasterers as Compo, was first i ntl ^duced to public notice by Messrs. Parker and Wyatt, "took out a patent for it, and who succeeded in obtaining 1it an extensive sale. f

It is prepared from the kind of stone called clay-ballSiseptaria, by being, after the manner of manufacturing P‘ fl ® ^first broken into pieces of a convenient size, slowly calc ,I,ein kilns or ovens, and afterwards ground to a fine P°' vl , v6and put into proper casks, great care being taken to preseiit from damp. Two parts of this composition, with tnparts of clean grit-sand, will form a very durable substi ^ _for stone. In selecting the sand, great care must be ta j,to procure it free from clay or mud, and of a sharp and bt* 1ing quality, or it must be washed until perfectly clean. j 3This composition, when it is intended to compo, as 1termed, the exterior of a building, is thus used:—

After the walls have been well soaked with water, \cement must be prepared by the hawke-boy on a stiff b? {0made for the purpose, adding as much water as brings >the consistency of paste, but no more must be mixed 1can be used in ten minutes. It must be laid on wi*b ^greatest possible expedition, in one coat of three-q uaI - t [jof an inch in thickness, and after being well-adjusted ' {0the floating-rule, the hand-float must be incessantly use , jtbring it to a firm and solid surface before it sets, whi cdoes in about fifteen minutes. _ .^e

The work should then be drawn and jointed to 11111well-bonded masonry, and afterwards coloured with ® jcomposed of five ounces of copperas to every gallon of ' v—a sufficient quantity of fresh lime and cement—and t°whole adding the colours necessary to imitate any P al tlstone that may be required.

Terra Cotta , or artificial stone, is an excellent and du ^composition, advantageously used at the present day 1kinds of exterior decoration. It is a compound of P’P e aI) dstone-bottles, glass, and flint, well pounded together,sifted through a fine sieve, a small portion of silverafterwards added. . j, J)» s

Bailey’s Composition is also a valuable invention, wn . oll tbeen used with great advantage in various situations, v* g tbeing at all injured by winter. The exteriors of r® t jiisthe public buildings in the metropolis are covered wi 'scomposition, amongst which is the Colosseum in the 1 »Park. tb ot

It is simply a mixture of lime and sand, the strel !^ c li > !the lime being preserved by the peculiar manner in ^ er b 3is prepared. In its manufacture, chalk should Iie ^. c tf'used ; it ought always to be made from lime-stone,bonate of lime. The lime, being taken before being ^ g j, 9 toand ground to powder, must be placed in iron-bound 1J ju 3tprevent the admission of air or damp. When used,be mixed with one-third its quantity of sharp river-smanner of working it being the same as that ocement. See Mortar, Grout, Stucco , and Conck* j ; a l o >CEMETERY, a sacred place, set apart for thethe dead. The term is of Greek derivation, s jS n j,jj r j s ti» 11place of rest or sleep,” and was applied by the early vto common places of interment.

The subject of burial in towns has oi mio -^iprominent a place in public estimation, that the e

has of late