go, Dr. Henry’s Analysis of several Varieties 
allowed to subside to the bottom of the pan, along with the 
salt first formed, and with some sulphate of lime ; and are 
afterwards raked out. These two operations are called clearing 
the pan. Some brines scarcely require them at all, and others 
only occasionally. The whole of the impurities, however, are 
not thus removed ; for a part, subsiding to the bottom, forms 
a solid incrustation, termed by the workmen pan-scale. The 
portion of this, which is lowest, acquires so much induration 
and adhesion to the pan, that it is necessary to remove it, once 
every three or four weeks, by heavy blows with a pick-axe. 
These sediments are formed, also, in making the other varie- 
ties of salt. 
In preparing common salt, the brine is first raised to a boil- 
ing heat, with the double view of bringing it as quickly as 
possible to the point of saturation, and of clearing it from its 
earthy contents. The fires are then slackened, and the evapo- 
ration is carried on for 24 hours, with the brine heated to 160* 
or 1 70° Fahrenheit. The salt, thus formed, is in quadran- 
gular pyramids or hoppers, which are close and hard in their 
texture. The remainder of the process is similar to that of 
making stoved salt, except that after being drained, it is car- 
ried immediately to the store house, and not afterwards 
exposed to heat, an operation confined to the stoved salt. 
The large grained flakey salt is made with an evaporation 
conducted at the heat of 130 or 140 degrees. The salt thus 
formed, is somewhat harder than common salt, and approaches 
more nearly to the cubic shape of the crystals of muriate of 
soda. 
Large grained or fishery salt , is prepared from brine heated 
only to ioo° or 110° Fahrenheit. No perceptible agitation. 
