GEOLOGICAL SOCIETY OF MANCHESTER. 



151 



The paper was divided into two parts : the first treated of 

 the nature of the Cheshire brine, and its analytical contents ; 

 the second, on the origin of the Cheshire rock salt. Before 

 proceeding to the subject matter of the paper, the strata in 

 which salt had been found were shortly mentioned, and it 

 was shown that the position of the Cheshire salt was in the 

 upper beds of the new red sandstone. In treating of the 

 nature of brine, Mr. Ormerod quoted the opinions of Dr. 

 Holland, Messrs. Lyell, and Murchison, and Dr. Daubeny ; 

 all agreeing that brine was caused by water melting the upper 

 surface of the highest bed of salt. He then showed, that the 

 water could not be impregnated by percolating through the 

 overlying strata, as these beds are scarcely permeable for 

 water; and, even if they were so, the quantity of muriate of 

 soda derived from them would be too small to supply the 

 brine springs. The tables of analysis were compiled from 

 " Holland-'s Agricultural Survey of Cheshire,'^ and from a 

 paper of Dr. Daubeny^s in the ^' Philosophical Transactions 

 for 1830.^' The last showed, that the Cheshire brines of 

 Northwich, Middlewich, Nantwich, and Winsford, contained 

 iodine, bromine, chloride of calcium, magnesium and sodium, 

 sulphate of lime, and also a portion of insoluble matter. It 

 appeared that no series of analysis which might be con- 

 sidered as really comparative, had as yet been made ; but 

 that, making a slight allowance for a temporary variation in 

 the strength of the brines, the similarity in the proportions 

 of their component parts was very great. After mentioning 

 the existence of red colour in salt lakes of the present day, 

 which was caused in some cases by the presence of an 

 infusorial animalcule, the Monas Dumalii, which animalcule 

 is also found in the salt at Cardona, Mr. Ormerod stated that 

 he had examined the Northwich rock salt to discover the 

 cause of the red colour : he had not, however, as yet ex- 

 amined more than a single specimen ; the colouring matter 



