186 STRENGTH OF THE BRINE. 



of the shale, and seemed to show that when this shale 

 was deposited in the state of a fine mud, it was impreg- 

 nated with salt — probably was at the bottom of a salt 

 lake, liable to be dried up or concentrated by evapora- 

 tion, and that, when so concentrated, the salt crystallised 

 among the mud in large crystals, as impure salts usually 

 do, and impressed the shapes now seen upon the plastic 

 mud. No solid salt, however, has ever been found in 

 connection with these pseudo-morphic masses. It has no 

 doubt been long dissolved out by rain and spring waters 

 sinking through from above. But while the salt-springs 

 which occur throw light on their formation, these crys- 

 tals, on the other hand, explain in what way the upper 

 Silurian strata of western New York have in so many 

 places become impregnated with salt. 



The wells or borings from which the brine is obtained 

 are sunk in the marshy ground which borders the Onon- 

 daga Lake. This lake, which is about five miles long 

 and one mile broad, rests on a bed of impervious marl, 

 beneath which lies a thick deposit of drift, occupying a 

 valley hollowed out of the shales of the salt-group. 

 Into this drift the borings have been carried to a depth 

 of nearly 350 feet; and the supply has generally been 

 more copious, and the water more strongly impregnated 

 with salt, the deeper the boring has penetrated. 



If the quantity of salt contained in water which is 

 saturated be represented by 100, that contained in the 

 strongest springs near Syracuse is 76. A hundred- 

 weight of salt is obtained from about 700 gallons of sea- 

 water ; but of the water from these springs 80 gallons, on 

 an average, yield an equal weight — or 100 pounds of 

 the water yield from 15 to 18 pounds of salt. 



It is found, however, that, by constant pumping, the 

 water gradually becomes weaker in salt, and unfit for 

 profitable use ; when either the water in that well must 

 be allowed to rest for a time, or new borings must be 



