MUR

MUR

( 123 )

One pound of this analyzed by Klaproth is

compofed as follows:

oz. dr. gr,

Moidure - _- -- i6o

Muriated lime - --i io

•-Magnefia -- 10

--— Soda ---- 4 4 4 °

Carbonat of lime - - - 1 2 30

Sand -- 33 °

Sulphat of lime - - - 7 60

16 o o

The mother water , or liquor left in the faitpan after all the fait that it is thought proper to■work off is taken out, is a very denfe bitterfluid. Its fpecific gravity is as high as 1.218.Fifty cubic inches yielded by evaporation 5440grains of dry fait, compofed of

Muriated lime ----- 660

——-Magnefia - - - 84°

Sulphat of lime - - - - 100

Common fait ----- 3840

5440

It is remarkable that the muriated magnefiais here a fourth more than the muriated lime,whereas in the brine, both rough and graduated,it is not more than -3— or At of the muriatedlime. Hence much of the latter muft bedecompofed during the boiling, to whichKlaproth attributes the drong fmell of muriaticacid perceivable when the evaporation is nearlycompleated.

A very full and accurate account of a 11 theprocefles employed in the large falt-works ofSalins, Moyenvic , and other brine fprings inFranche Comte in the South of France on theborders of Savoy, is given by Nicolas, whoexamined them on the fpot. e

We fhall not tranfcribe it at large to avoidrepetition, the general method being that al-ready mentioned, viz. of concentrating thebrine by graduation, then boiling down in ironpans. But fome varieties of practice and othercircumdances contained in this valuable me-moir are worth relating.

The brine gives by analyfis the followingingredients. One French pound (of 16 oz.and 576 grs. to the ounce) contains of

oz. grs.

Muriat of foda - - 7 — 529

Sulphat of lime - - 23

Sulphat of foda - - 73

Muriat of lime and magnefia 81

Three kinds of fait are made at Salins,namely, large grained, fmall-grained, and loaf-falt. The common or fmall grained is thatwhich is made at a boiling heat, continued tothe lad. The large-grained is made in fmallpans placed contiguous to the boiling pans andlupplied by the fame fire, the flues being con-tinued under them. The heat in thefe is butflow and the evaporation moderate, which al-lows the fait to form in larger crydals. Theearthy-faline fcum which forms during theboiling, is afterwards lixiviated to extract thefait which it contains. The fchlot or pickingsfrom the pans contains much Glauber’s faitwhich is alfo extradited by hot water, and whenthe folution is fo far concentrated that it wouldcryftallize by cooling, it is ftirred conftantlytill cold, which makes the fait aflume a needledform like the common Epfom fait, and is foldas fuch.

A very ingenious plan has been introducedhere of applying the principle of evaporationby the atmofphere, not only to the concentra-tion of the brine but to the actual crydallizationof the fait which it contains. For this purpofethe brine after common graduation on faggots,is heated in the pan till it begins to fait. It isthen conveyed to another graduating houfeabout 250 feet long, divided by party wallsinto fix arches. Thefe fupport troughs extend-ing the whole length of the building and fur-nifhed with proper holes for the brine to falldown. The fpace under each arch is filledwith forty rows of endlefs cords'ftretched verti-cally on wooden frames, each of which contains25 double cords parallel to each other, andabout three inches afunder. The whole build-ing contains 6000 of thefe double cords about3 or 4 lines in diameter, and about 30 feetlong. The flooring of the building is made offir planks well put together, and gently Hopingto one end to convey the brine as it falls, intoa large refervoir from which it is again pumpedup to the upper trough. The fide of the build-ing mod expofed to the weather is protedfed bya canvas. The hot brine as it pafles from theboiler is fent into the upper trough and thenfalls down every one of the cords in a copiousdream, round which the fait gradually cryfial-lizes in a dalaftitical form. When the crudof fait forms a cylinder from 2 to 2-f- inches indiameter it is taken off, and the procefs repeated.Each operation produces from 3500 to 4000quintals of .excellent fait, and requires about amonth to be formed; and as this work can only

c Ann, deChera tom. xl.