176 Rock Salt and Salines of the Holston. 



the deposition of the salt. Not having a freshly quarried speci- 

 men, I have been unable to ascertain whether the gypsum over- 

 lying the salt, or that associated with it, is anhydrous. This 

 brine is saturated, and like that of Droitwich and Cheshire, is 

 undoubtedly derived from the solution of fossil salt. This origin 

 of the brine will explain its general uniformity in strength and 

 composition in the different wells, when unaffected by infiltrated 

 fresh water, as well, as its slight variation in strength by contin- 

 ued working ; it being well known that where the salt exists in 

 the rocks interstitially, the brine is soon weakened by the exhaus- 

 tion of the saline matter, rendering it necessary to deepen the 

 shafts from time to time. Does not this origin explain the sin- 

 gularly low temperature of the wells ? which in one of them is 

 the same as that of the springs of the vicinity, and in the others, 

 but one or two degrees above them. The temperatures of the 

 respective wells are as follows 



Anthbny well, 226 feet in depth, . . 54£ 



53£ 



Kings " 206 " 

 New " 214 " 



<c 



a 



55i 



Mrs. Preston's spring, (average temperature of the 

 springs of the county,) .... 53^ 



Spring at salt works, 



52J 



This slight elevation of the temperature of the wells is less 

 than is due to their depth, and may perhaps be owing to the 

 cooling influence of saline solution. The brine differs in com- 

 position from the rock salt only in the absence of the perox- 

 ide of iron, and in containing a larger proportion of sulphate of 

 lime; the former existing in the rock salt in the state of an inso- 

 luble peroxide is not dissolved, and the latter is derived from the 

 associated strata. The annexed analysis is of the brine of the 

 neiv Artesian well } bored a few months since to the depth of two 

 hundred and fourteen feet, water having been obtained at the 

 depth of one hundred and ninety three feet. One thousand 

 grains of the brine contain 



Chloride of sodium, .... 240.52 



" calcium, ... .08 



Sulphate of lime, .... 5.35 



Water, 

 Alumina, 



754.05 

 a trace. 





