brine is fully saturated there is a state of equilibrium as it 
were. If we reduce the quantity of water this balance is 
disturbed and a portion of the salt crystallizes out, until 
the brine is again at saturation point. If we continue 
driving off the water the salt continues to crystallize and 
deposit. This process might go on till all the water was 
expelled and all the salt crystallized ; but in the process of 
manufacture this never occurs, as the pan is replenished with 
brine from time to time. 
During the manufacture of salt the laws regulating the 
formation of salt crystals may be clearly seen. The kinds 
of salt manufactured do not vary at all in their constituent 
parts, but merely in the size of the crystal or “ grain,” as it 
is called. To sum up the whole process in a few words, we 
may say generally that the larger the crystal the less the 
heat and the longer the time required to make the salt ; 
the smaller the crystal, the greater the heat, and the less 
time required to make the salt. Brine boils at 226° Fahren- 
heit. Boiled salts are taken out of the pan two or three 
times in twenty-four hours. Common salt, such as used 
for soaperies, chemical works, &c., every two days. Fishery 
salt remains in the pan, according to the grain, from six to 
fourteen days; Bay salt, three weeks to a month. The manu- 
facturer, by manipulating his brine, can make the crystal more 
or less flakey, or more or less solid as he wishes, but the general 
principle is not altered. Foreign ingredients, such as gela- 
tinous matter, or alum, have very peculiar effects on the brine 
and on the salt crystal. Bay salt is made at a temperature 
of about 90° ; Fishery, from 90° to 140° according to grain. 
Common salt, 170° to 180°. There is no exactitude main- 
tained on this point, nor is it material, as a slight variation 
in the grain makes no difference in the sale and use of the 
salt. 
The manufacture of salt is extremely simple, almost 
rude; yet the simple plan in use for ages has been found 
