SOLAR EVAPORATION 41 



formed increase in size, new ones make their appearance 

 and soon the entire bottom of the room is covered with 

 them. It is the custom of the manufacturer, while this is 

 going on, to introduce a sufficient amount of saturated pickle 

 from the lime rooms to replace the evaporated water and 

 thus keep the salt well covered. 



Since the brine contains besides salt, ferrous carbonate 

 and gypsum, other constituents ; namely, potassium, calcium 

 and magnesium chlorides and magnesium bromide; a com- 

 parison of the chemical composition of the brine with that 

 of the pickle is but proper in this place. From Dr. Goess- 

 mann's* experiments it appears that a brine having the 

 chemical composition given under No. i, produces a pickle 

 of the composition given under No. 2. 



No. 1 Brine No. 2 Pickle 



Specific gravity 1 . 1225 1 . 2062 



Calcium sulphate 0.5772 per cent 0.4110 per cent 



Calcium chloride ., 0.1533 " " 0.2487 " " 



Magnesium chloride 0.1444 " " 0.2343 " " 



Potassium chloride .. 0.0119 " " 0.0194 " " 



Magnesium bromide 0.0024 " " 0.0039 " " 



Ferrous carbonate 0.0044 " " 



Sodium chloride 15 • 53*7 " " 25.7339 " " 



Water 83.5747 " " 73-348S " " 



In this experiment Dr. Goessmann employed ioio parts 

 of the above brine and obtained 623 parts of pickle, while 

 3.28 parts of calcium sulphate had crystallized out and 383 

 parts of water evaporated. While, then, the ferrous carbon- 

 ate had been entirely removed and the calcium sulphate 

 decreased more than one half, the salt and the soluble cal- 

 cium and magnesium chlorides had increased in the propor- 

 tion of their original quantities. Whenever a sufficient 

 amount of salt has accumulated in the salt rooms it is har- 

 vested. This occurs about three times during a season. 

 The process consists in raking it together on the side of the 

 room next to the road and putting it into small perforated 



* "Report on the manufacture of solar salt, etc." Syracuse 1864. 

 6 



