214 Natural History of the Cheshire Rock- Salt District. 



some of the excepted instances appear to have a local rela- 

 tion to the southern or central plain. This is the case with 

 the salt springs ot Dirtwich, in the south-western angle of 

 Cheshire; wilh a spring of very weak brine latclv found at 

 Adderiey, in the northern extremity of Shropshire ; and 

 probably also with other saline springs which occur in the 

 contiguous parts of Flint and Denbighshire. At Dunham, 

 however, in the north of Cheshire, we find a weak sp'ing, 

 which cannot strictly be considered as connected with the 

 formations of the southern plain. At Barton and Adling-r 

 ton, in the southern parts of Lancashire, bnne springs 

 likewise appear; and it is not improbable that other in- 

 stances of the same kind may occur in the northern portion 

 of the great plain. It appears possible, however, that these 

 weak springs may derive their saline contents, not from 

 distinct subjacent beds of the fossil salt, but merclv from 

 beds of clay or argillaceous stone, strongly in)pregnated 

 with particles of the muriate of soda. 



Maru/factiire of JVIdte Salt. 



It would be foreign to the object of this paper to enter 

 with minuteness into the natural history of the salt springs, 

 or into the processes employed in the manufactirt-e of white 

 salt. Those members of the Society, who may wish for 

 further information on these subjects, I beg leave to refer 

 to the Survey of Cheshire before noticed. It may be suf- 

 ficient here to state a few of the most general and impor- 

 tant facts. 



The brines met with in this district are very generally 

 formed by the penetration of spring or rain waters to the 

 upper surface of the rock salt, in passing over which they 

 acquire a degree of strength, modified by several circum- 

 stances, which it would be needless to detail. Their aver- 

 age strength, however, appears to be much greater than 

 that of the springs met with in Hungary, Germany, or 

 France. At Winsford, North wich, Anderton, Lawton, 

 Roughwood, Wheelock, and Middlewich, where all the 

 principal salt works are situated, the brine springs contain 

 between 23 and -2Cy per cent, of the pure muriate of soda ; 

 and in some of the springs at Anderton, the proportion 

 stands as high as 26 566 per cent, a ver\' near approach to 

 the perfect saturation of the brine. The earthy salts held 

 in solution together with the nuiriate of soda arc principally 

 muriate of magnesia and sulphate ot lime; the qnantitv of 

 these varying from -/j- per cent, to 2 or to 2i per cent, in dif- 

 ferent 



