44 Mr. H. Holland on the Cheshire Rock-salt District. 



It may be sufficient here to state a few of the most general and im- 

 portant 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 circumstances, which it would be needless to 

 detail. Their average 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 25 and 26 per cent, of the pure mu- 

 riate of soda ; and in some of the springs at Anderton, the proportion 

 stands as high as 26.566 per cent, a very near approach to the per- 

 fect saturation of the brine. The earthy salts held in solution 

 together with the muriate of soda are principally muriate of mag- 

 nesia and sulphate of lime ; the quantity of these varying from -"- 

 per cent, to 2 or to 2|- per cent, in different springs. The brine 

 being pumped out of the pits, is first conveyed into large reservoirs, 

 and afterwards drawn off as it is wanted, into evaporating pans, 

 made of wrought iron. Here heat is applied in a degree determined 

 by the nature of the salt intended to be manufactured, and various 

 additions are made to the brine, with a view either to assist the 

 crystallization of the muriate of soda, or to promote the separation of 

 the earthy salts. The latter exist in a very small proportion in the 

 manufactured salt, and cannot be supposed in any degree to affect 

 the uses to which it is applied.* The importance of the Cheshire 



* In reference to the chemical character of the different varieties of salt, an excellent 

 paper by my friend Dr. Henry will be found in the Philosophical Transactions for the 

 year 1810. Part I. 



