66 IODINE. 



It is decomposed by the electric spark into hy- 

 drogen and chlorine. 



It is readily absorbed by water, which then 

 becomes very acid, and forms the liquid muriatic 

 acid. 



The muriatic acid, called also the marine acid 

 and the spirit of salt, is in very common use. It is 

 obtained, as above-mentioned, by distilling sea salt 

 and sulphuric acid. It exists in a state of combin- 

 ation with alkalies and earths in the mineral 

 kingdom in great quantity, chiefly with soda, lime, 

 and magnesia. With soda it forms muriate of soda, 

 common or sea salt, with which every part of the 

 ocean is impregnated, and also some lakes. Mu- 

 riate of soda also exists in the form of a rock in the 

 earth, whence it is extracted : it is called rock salt. 

 The most considerable mines of rock salt are in 

 Poland ; extensive mines are also worked in Hun- 

 gary, Spain, and Cheshire in England. Muriate 

 of soda is obtained also from the sea water, by 

 driving off the water by evaporation ; and this is 

 done either by exposing salt water in shallow places, 

 called saltpans, to be evaporated by the heat of the 

 sun, or by boiling salt water in vessels, or by these 

 methods combined. Muriate of soda, so procured, 

 is always contaminated with muriate of magnesia 

 and muriate of lime, from which the salt is puri- 

 fied by different processes. 



IODINE. 



This substance, considered as a simple body, has 

 been but lately discovered. It exists in certain 

 marine plants, and is procured from kelp, which is 



