MUR

MUR

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The whole procefs of boiling, purifying, andevaporating the brine, is performed'in this (inglepan.

The brine after (landing fome days in therefervoir, is pumped into the pan.. Whenheated to about ioo° it begins to grow turbid,owing to the depofition of the carbonat of limeand of iron (if any) by the expulfion of the car-bonic acid which held them in folution. Thisforms a fcum on the furface of the brine whichis partly removed by a flamming difh, butmuch of it falls to the bottom, and if fufFeredto remain would materially injure the quality ofthe fait. To clear it out the brine is evaporatedtill it begins to fait, that is, till a portion of themuriat of foda begins to feparate, and this fallingto the bottom mixes with the carbonat of limeand gives it a body, which enables the workmanto draw it out. This is carefully done, and thefediment thus obtained (called clearings) isthrown away, which from a pan of 24 feet by27, ufually amounts to about three or fourbuflieis. The evaporation is then continued ata boiling heat, and the fait gradually colleftsat the furface and falls to the bottom inbeautiful cryftals of a pure and delicate white,where the brine is good. As the procefs ad-vances and the fait collects in quantity, it isfifhed out from the bottom of the pans by woodenveffels, and poured into large hollow woodencones, with a hole at bottom, and fufpendedround the fide of the pans. Here it drains,and the drainings drop again into the pans.When the procefs is compleated and the contentsof the pan evaporated almoft to drynefs (whichufually takes a fi igle day and a night) the conesfull of the fait are taken to a large room madevery hot by (loves, where they remain tillthoroughly dry.

The .grain of the fait is determined by therapidity of the evaporation and the degree ofheat ufed. In the common (alt-making thew-ater is evaporated at a full boiling heat, that is,as fail as poffible, and hence the grain is fmall,and the fait comparatively foft. The contentsof a (ingle pan are ufually worked'off in twenty-four hours, except from Saturday to Monday,when two days are taken, and hence a largerand harder grained fait is made, which is muchefteemed in the country for fairing cheefe.

It is found by experience that fome brineswill not readily fait by mere evaporation, butthat fome addition is required to make them workwell and the fait fall regularly. This additionis generally calve’s feet j lly, fomet’.mes glue,fometimes white of eggs, fometimes blood, and

in (hort any animal or vegetable mucilage feemsto anfwer the purpofe. It is ufual to have(landing in a corner of the pan an earthen veflclcontaining eight or ten pair of calve’s feet, towhich hot brine is added to extraril the jelly,and after the clearings are removed and the brinebegins to fait, the workman adds a little of thejelly at diferetion. The precife ufe of this ad-dition is by no means obvious, nor is it abfo-Iutely neceffary, but long experience has (hewnit to be ufeful in many kinds of brine.

Another difficulty fometimes arifes. Ingeneral the brine when it once has begun tofait, goes on to work well to the lad, everypart of the furface being fulficiently coveredwith fmall cryllais of fait, which foon growinto a group forming a fmall floating iflandof (alt, which foon finks to the bottom by itsown weight, and leaves a clear furface above,which again is covered in the lame manner.But fometimes from Come unknown caufe, athick fhapelefs crult of fait forms rapidly over• the whole pan, which loon hardens to a dryfloating cake of fait, preventing in a great mea-fure the efcape of the (team, and materiallyretarding the procefs. To remedy this a fmalllump of butter, not more than about half anounce, is thrown into the pan, which quicklymelts and diffufes itfeif over the dry cake offait, and caufes it to break up and link, afterwhich the fairing goes on well.

After the brine has been evaporated nearlyto drynefs, and indeed during the latter part ofthe boiling there is depofited on the bottom andfuies of the pan a hard white (aline and earthycruft, which (Irongly adheres to the pan, andis partly fufed to its furface by the intenfity ofthe fire in proportion as the fides become dryby the lofs of liquid.

This cruft daily accumulates and producesmuch inconvenience, partly' by injuring thequality of the fait, but chiefly by increafing thediftance between the fire and the brine, andforming a thick coating through which the heatpenetrates with difficulty. Hence it becomesneceffary about once a month to difeontinue theboiling for a day, and to pick and beat off thiscruft with hammer and chiflei often to the greatinjury of the pan itfeif. The pickings or pati-feratch as they are aifo called are thrown away.Their analyfis wili be mentioned af erwards.

A very large-grained and beautiful fait ismade at Liverpool and fome other places byvery flow evaporation of faturated brine, andfirings or (ticks are put into the pan on whichthe cryllais form, as in the making of fugar- ■

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