46 BULLETIN OF THE NEW YORK STATE MUSEUM 



interval by a third arch only a foot wide and so on. These 

 arches are called rings and their width decreases from the 

 front of the pan towards the end while the air spaces in- 

 crease in width in the same direction. Beyond 20 feet from 

 the front of the first section of the pan they cease altogether. 

 To convey the heat as close to the pan bottom as possible, 

 beyond the last arch, the flues are usually filled in with earth 

 or plaster, and thus the distance between the pan and flue 

 bottom is between 3 and 4 feet or even less, at the end of 

 the first pan where a perpendicular wall, a so-called bridge 

 wall, reduces the space to about i| to2 feet, through which 

 the products of combustion pass under the back pan and 

 finally into a common chimney. 



For the purpose of draining the salt, before it is con- 

 veyed to the storehouse an inclined wooden platform, the 

 so-called " drip " is constructed along the entire length of 

 both pans on either side, resting on the inclined iron sides 

 of the pan. 



The so-called settling of the brine is the same as in the 

 kettle method, with this difference, that the settled brine in 

 consequence of the greater number of cisterns and their 

 greater capacity remains for 4 to 5 days undisturbed. If 

 it is the intention of the manufacturer to make the so-called 

 " Factory Filled Salt " used for the dairy and the table, the 

 settling with caustic lime is followed by a second settling 

 with a certain quantity of carbonate of soda or soda ash as 

 it is usually called by the workmen. The sodium carbonate 

 is dissolved in salt water and the solution mixed with the 

 brine. The carbonic acid unites with any caustic lime in 

 solution in the brine, while the resultant caustic soda 

 together with the greater quantity of undecomposed 

 sodium carbonate decomposes the calcium and magnesium 

 chlorides forming calcium and magnesium carbonates and 

 common salt. Between the settlings with lime and sodium 

 carbonate 12 hours are usually allowed to intervene. 



After the pans are properly cleansed they are white- 



