294 



SKETCHES OF CREATION. 



Fig. 90. View of the Salt Works at Mason City, West Virginia. 



CHAPTER XXVI. 



SOMETHING ABOUT ROCK-SALT AND GYPSUM. 



COMMON salt, upon which the chemist has imposed the 

 more dignified title of chloride of sodium, is a mineral 

 almost universally distributed through the stratified por- 

 tion of the earth's crust. Like those other substances of 

 universal utility to man — petroleum, coal, iron, water, and 

 lime — it is supplied by Nature to every habitable region 

 of the terrestrial surface. Like lime, which is the chief 

 constituent of the bones and teeth of man and the other 

 vertebrates, the shells of molluscous animals, and the 

 mountains of coral accumulations reared in the bottom 

 of the sea, common salt also subserves the necessities not 

 only of man, but of the quadrupeds and various other ter- 

 restrial animals, including insects, and is the characteristic 

 constituent of sea-water, the home of two thirds of all the 

 animals now existing, and a much larger proportion of the 

 animals of former geological ages. 



