120 ECONOMICAL MINERALOGY. 



edly belongs to the saliferous series, is made up entirely of these crystals, varying in size from 

 one to eight inclies. One of these crystals, which I analyzed, has the following composition : 



Carbonate of lime, 26. 25 



Carbonate of magnesia, 19.35 



Oxide of iron, 4. 65 



Silica and alumina, or clay, 49 . 75 



Sometimes, however, the proportion of the carbonates is larger ; the crystals having their 

 surfaces covered with an incrustation of pure carbonate of lime, and their bases slightly rhom- 

 boidal. After an attentive examination of this interesting locality, I was led to the conclusion 

 that these had originally been crystals of common salt which had been dissolved out, and the 

 moulds thus formed again filled with clay, and subsequently incrusted by the percolation of 

 water charged with the carbonate of lime. That this latter process has been going on exten- 

 sively, is evident from the enormous quantities of calcareous tufa which are found in the 

 immediate vicinity. 



A writer in the Philosophical Magazine and Annals of Philosophy, in 1829,* from a review 

 of the facts stated by Mr. Eaton, thinks the water limestone intimately pervaded with the 

 chloride of sodium, which the moisture of the atmosphere, acting upon an exposed specimen, 

 and the water of the springs acting upon the rock in situ, extracts and dissolves. Hence 

 carbonate of lime is found in these brines, while the brines of the Cheshire and Droitwich 

 springs in England, which arise from the direct solution of rock salt, to which no carbonate 

 of lime is immediately contiguous, are either entirely free from it, or contain only a minute 

 proportion. 



The same author suggests that the crystals of chloride of sodiitm, which formerlj'' existed 

 in the strata, were deposited at the era of the formation of the saliferous rock, by the same 

 agency which in other parts of the world produced beds of rock salt ; and the salt has simply 

 heen dissolved out at a subsequent period by the percolation of water through the superin- 

 cumbent strata, leaving impressed in the rock cavities bearing the forms of the crystals ; and 

 such, without doubt, he affirms has been one source of the brine springs of this district. 



In confirmation of this view, a fact mentioned in Townson's Hungary is also adduced, viz. 

 that the lowest beds of marl in the great salt mines of Wieliczka are mixed with salt in small 

 patches and cubes. If water were to percolate slowly through this bed, the salt would be 

 dissolved, and cubic and other cavities left in the marl, if of a texture sufiiciently compact, 

 which would then present a similar appearance to the beds above described. 



But this theory, although so plausible at first sight, does not, it appears to me, satisfactorily 

 account for the formation of the large and solid crystals found at Camillus. The occurrence 

 of mere cavities may perhaps be well enough explained in this manner, but it should be re- 

 collected that the entire stratum of several feet in thickness is a mass of crystals. It is worthy 

 of suggestion, that these crystals, although they have the form of those of common salt, may 



♦ SiijiposeJ to be E. W. Braylcy, junior. 



