190 ORDER OF DEPOSITION OF THE 



300 acres are covered with vats for solar evaporation ; 

 and these, in 1848, yielded 713,000 bushels, while only 

 75 acres are occupied by the blocks^ which manufactured 

 upwards of 4,000,000 bushels of fine salt. About one 

 half of the coarse salt is crushed or ground, and sold 

 under the name of dairy salt, being preferred for dairy 

 purposes. 



In the order of deposition of the several ingredients of 

 the natural brine in the solar vats, Mr Vanuxem finds a 

 resemblance to, and an explanation of, the mode and 

 order of deposition of the several members of the Onon- 

 daga salt-group. '^ This group shows first a thick mass 

 coloured red w^ith iron, being its red shale." This cor- 

 responds w4th the oxide of iron first deposited in the vats. 

 " Above the red shales are the gypseous masses, towards 

 the upper part of which are the salt cavities " — (that is, 

 the hopper-shaped cavities in which crystals of salt are 

 supposed formerly to have existed.) " Above the whole 

 of these deposits is the sulphate of magnesia, its (former) 

 existence there being manifested by the needle-form cavi- 

 ties " in the rock.* This explanation is very natural, 

 and not void of beauty. It may require some modifica- 

 tions to adapt it to the local phenomena in detail — such as 

 the occurrence of the green and blue shales, the limestones, 

 and the calcareous marls. It is, however, neither an 

 unnatural nor unlikely general representation of the pro- 

 bable cause of some of the special chemical characters 

 exhibited by the several successive beds. 



A more refined examination of the salts successively 

 deposited in the open wooden troughs in which the water 

 is exposed to spontaneous evaporation might lead to inte- 

 resting results of another kind. The brine most probably 

 contains both iodine and bromine ; and it is possible that, at 

 a certain stage of the evaporation, the saline compounds of 



* Geology of the Third Dutrict, p. 109. 



