230 NEW YORK STATE MUSEUM 



point where the gypstmi is about to precipitate. The brine is then 

 drawn into- vats about 6 inches deep in which the g^^psum or " Hme " 

 deposits and the solution becomes saturated with respect to the salt. 

 This solution is called "pickle " and goes to the salt rooms where 

 the final stage is aecompHshed. The salt crystals are raked from the 

 fioor of the rooms about three times a season which in a good year 

 lasts from the' middle of March to the middle of November; The 

 vats are protected against rain by covers or roofs mounted on a 

 wooden framework so as to be moveable. Some idea of the size 

 of the industry in the flourishing days may be had from the statement 

 of the state superintendent of the Onondaga Salt Springs in his 

 report for 1894 that about 45,000 covered vats, each 16 by 18 feet, 

 were- then in use. This implies an evaporating surface of 12,960,000 

 square feet. The estimated investment represented by these 

 structures, with the storehouses and mills, at that time was placed at 

 $2,750,000. The crop of the solar salt in 1894 was 2,355,394 bushels 

 or 471,079 barrels. 



The artificial evaporation of brines is now conducted b}^ open 

 pans, by grainers and by the vacuum pan. Open kettles heated by 

 fire or- by steam coils are no longer in use. 



Open pans are to be seen in only a few plants, as they have largely 

 been superseded by grainers which are more economical of heat and 

 in which the process of evaporation is carried on with less frequent 

 interruptions. The high temperatures attained by direct fire are 

 likely to cause wai-ping of the pans and buckling of the arches, 

 necessitating- considerable expense for repairs. They have an ad- 

 vantage over grainers, however, in that the evaporation can be 

 hastened by rapid boiling which leads to finer crystals, as the quicker 

 the process of precipitation, after the saturation point is reached, 

 the finer will be the crystal particles. On the other hand they require 

 more attention. 



The pans are made of boiler iron and set in brick arches with fire 

 grates at one end from_ which flues conduct the heated gases imder-the 

 whole length of the pans. These latter are about 100 feet long and 

 25 to 30 feet wide, divided into a front and back section by a, trans- 

 verse partition. The brine after settling and liming which remove 

 the iron and mechanical impurities is conducted into the back pan 

 where it is preheated and then siphoned into the front pan 

 in which the final evaporation is carried out. When the salt 

 has formed a sufficient deposit in the pan it is raked out and additional 

 brine added. From time to time the operation is stopped to remove 

 the bittern and scale the pan which becomes encrusted with a deposit 

 of gypsimi. 



