20 BOARD OF AGRICULTURE. 



cal conditions, and of a different chemical composition, which 

 both requirements are governed by the peculiar mode of its 

 manufacture, I find it advantageous, in the interest of our 

 mutual understanding, to begin with a short sketch of our 

 modes of manufacturing the different kinds of salt, and to con- 

 clude with its various uses. 



I. Our Modes of Manufacture. 



There are two kinds of salt in commerce ; the " coarse saU,^^ 

 including the salt obtained from natural rock salt deposits and 

 the salt made from brines and sea-water by means of solar heat, 

 and the " common fine salt," or boiled salt, produced by arti- 

 ficial heat. The coarse qualities of salt are the results of a slow 

 evaporation; the fine qualities that of a rapid evaporation. 



ON COARSE SALT. 



The coarse qualities are manufactured from sea-water and 

 from brines. In France, Spain, Italy, Portugal, the West 

 Indies, and along the shores of both the Atlantic and Pacific 

 oceans on our continent nearly all the coarse salt made from 

 sea-water is produced in basins along the seashores. These 

 basins are either natural or artificial ; several of them are, in 

 either case, connected in such a manner as to admit of a sys- 

 tematical working of the saline solutions in their different stages 

 of concentration. In Ohio, Virginia, Michigan, New York, 

 and, of late, in Nebraska and Kansas, where the natural brines 

 are used for the manufacture of coarse salt are preferred, wooden 

 vats, protected by wooden covers — for the frequency of rain- 

 showers throughout the more favorable portions of the year, and 

 the low temperature at night during spring and fall, interfere 

 very seriously with a successful evaporation, and thus econom- 

 ical manufacture", in open basins ; wooden vats, with suitable 

 movable covers, secure also a cleaner article. The rules adopted 

 in the construction and systematic arrangements of these vats 

 or basins are prescribed by the composition of the brines or saline 

 solutions turned to account for manufacturing purposes. A 

 short description of our most extensive solar salt works (Onon- 

 daga Co., N. Y.) may serve here as a general illustration. 

 The brines of Onondaga are of a very good quality ; they con- 

 tain a considerable quantity of sulphate of lime (gypsum), a 



