CEM

CEM

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• well. If fmeared with white of egg inftead ofwater, it adheres {fill clofer.

Another very convenient lute is linfeed mealmoiftened with water to a proper confidence,well beaten, and applied pretty thick over thejoinings of the veflels. This immediately ren-ders them tight, and the lute in fome hours driesto a hard mafs. Almond pafte will anfwer thefame purpofe.

The ufe of the above lute is fo extenfive thatno other is required in clofing glafs veflels inpreparing all common diftilled liquors, and it•will even keep in ammonia and acid gaffes for alonger time than is required for moft experi-mental purpofes. It begins to fcorch and fpoilat a heat much above boiling, and thereforewill not do asr a fire lute. It is Hill firmer anddries fooner when made up with milk, or lime-water, or weak glue.

A number of very cohelive cements impervi-ous to water, and moll; liquids, and vapors, andextremely hard when once folidified, are madeby the union of quick-lime with many of thevegetable or animal mucilaginous liquors. Thevariety of thefe is endlefs. We may firft men-tion the following as it has been extenfively em-ployed by chemilts for centuries. Take fomewhites of eggs with as much water, beat themwell together, and fprinkle in fufRcient flackedlime to make up the whole to the confiftenceof thin pafte. The lime fhould be flacked bybeing once dipped in water, and then fufferedto fall into powder, which it will do fpeedilywith great emiffion of heat, if well burnt. Thiscement fhould be fpread on flips of cloth andapplied immediately, as it hardens or fiets veryfpeedily. While hardening, it may be of ufe tofprinkle over it fome of the lime in fine powder.This cement is often more Amply, and as con-veniently managed by fmearing flips of linen onboth fides with white of egg, and, when appliedto the joining of the veffel, fhaking fomepowdered lime over it. It then dries veryfpeedily.

Another lute of the fame kind, and equallygood, is made by ufing a ftrong folution of glueto the lime, inftead of the white of egg. It fetsequally foon, and becomes very hard. A mix-ture of liquid glue, white of egg, and lime,makes the lutd’ane, which is fo firm that brokenveflels united with it are almoft as ftrong aswhen found. None of thefe lutes howeverwill enable thefe veflels to hold liquids for anygreat length of time. Milk or ftarch with lime•make a good but lefs firm lute.

A very firm and Angular lute of this kind is

made by rubbing down fome of the poorellflammed-milk cheefe with water to the confift-ence of thick foup, and then adding lime andapplying as above. It anfwers extremely well.Lime and blood with a fmall quantity of brick-duft or broken pottery ftirred in is ufed in fomeplaces as a very good water-cement for cellarsand places liable to damp.

Paris plafter mixed with egg, milk, glue,ftarch, or any mucilaginous liquor, alfo makesa good lute.

Some artifts mix other earths with the abovematerials. Thus a very good cement is madewith equal parts of clay and lime, about -j offlour and white of egg; or as is ufed by manyof the aqua-fortis makers, a mixture of colco-thar, lime, and white of egg.

All the above-mentioned cements with limebecome very hard by drying, infomuch thatthey cannot be feparated from glafs veflelswithout the help of a {harp knife and fome vio-lence, and hence delicate veflels and long thintubes cemented with it are apt to break whenthe apparatus is taken down, and fometimeseven by the mere force of contraction in fetting.It is a great advantage however that they maybe applied immediately to any accidental crackor failure of the lute already on, notwithftand-ing a ftream of vapour is burfting through, andin large diftillations it is of advantage always tohave fome of the materials at hand.

Thefe lutes will not confine very corrofiveacid vapours perfectly for a great length oftime, but will anfwer for other purpofes, parti-cularly where a complicated apparatus is to bekept fteadily united and air-tight. They willbear nearly ared-heat without material alteration.

Another kind of lute which is the moft per-fect for confining acid vapours for any lengthof time, and which never hardens to an in-convenient degree is the fiat lute as it is called.This is made by taking any quantity of goodclay, tobacco-pipe clay for example, thoroughlydry, but not burnt, powdering it in an iron mor-tar, mixing it gradually with drying linfeed oil,and beating them for a long time to the con-fiftence of thick pafte. Much manual labour isrequired, and it fliould be continued till themafs no longer adheres to the peftle. Thenmake the edges of the glafs or other veflelswhere it is to be ufed perfectly dry, and applythe lute carefully, and it will ftand the longeltprocefs without _ failing. This grows firmenough to retain its place and to hold the veflelstogether, but may readily be feparated by aknife. This lute much improves in adhefive-