SALT FROM SEA WATER 13 



would yield approximately 4,500,000 cubic miles of salt! In comparison with 

 these figures the output of the rock salt beds at Stassfurt, Germany and in Ohio. 

 Michigan, New York, and Kansas appears trivial. 



Common salt is more or less impure sodium chloride (NaCl), composed of 

 39.39 per cent sodium and 60.61 per cent chlorine. It is a white, lustrous solid 

 which generally crystallizes into cubes. In solution with water it has a bitter, 

 brackish taste and is neutral to indicators. Pure sodium chloride is slightly hygro- 

 scopic, taking up about one-half per cent of the moisture from the air at ordinary 

 room temperature. It melts at 1421° F (772° C) and vaporizes rapidly at white 

 heat. A saturated aqueous sodium chloride solution crystallizes as the hydrate, 

 NaC1.2HA from 19.4°F(-7°C) to -7.6° F(-22° C), and NaCl.lOH.O sepa- 

 rates at -9.4° F (-23° C). 



Table 4. Solubility of Sodium Chloride in 100 Parts by Weight of Water. 



Sodium Chloride 



32.73 

 33.49 

 34.22 

 35.52 

 35.74 

 35.87 

 36.13 

 36.64 

 36.98 

 37.25 

 37.98 

 38.22 

 38.87 

 39.61 

 40.35 



Concentrated solutions of sodium chloride possess antiseptic properties because 

 it extracts water; therefore, salt is often used in the preservation of meat, fish, and 

 other food products. As well as for seasoning food and preserving it, salt is used 

 in large quantities for the curing of hides, the making of brines for use in refrigera- 

 tion and ice factories, the making of dyes, and the preparation of sodium and 

 chlorine. Commercially, common salt is the chief source of sodium of all sodium 

 compounds, except sodium nitrate which is found in Chile. Large quantities of 

 salt are used for making soda ash and caustic soda. Metallic sodium is prepared by 

 the electrolysis of molten sodium chloride, chlorine being obtained simultaneously. 

 From salt is prepared practically all commercial chlorine, a few compounds of 

 which are: sodium hypochlorite, sodium chlorate, sodium perchlorate, bleaching 

 powder, hydrochloric acid, and silver chloride. Industries which use large quan- 

 tities of salt are: oil refining, hard soap, ceramic, various metallurgical, paper 

 works, and textile. 



In Table 5 on page 14 are presented data collected by the United States 

 Bureau of Mines, indicating the quantities of salt sold or used for various pur- 

 poses by producers in the United States in 1947 and 1948. It is evident from these 

 figures that the food and feed industries use more evaporated salt than any 



