Salt. 31 



seeming satisfaction as the ordinary civilized 

 child will a lump of sugar. 



All animals seem to require salt, and it is 

 claimed by those who have tried the experi- 

 ment that after one has refrained from the 

 use of salt for a certain length of time the 

 craving for it becomes exceedingly painful. 

 It is most likely that the taste for salt is a 

 natural craving. In any event, whether it is 

 a natural or an artificial taste, it has become 

 an article of the greatest importance in the 

 preparation of food, as well as on account of 

 its use in the arts. Salt is a compound of 

 chlorine and sodium. In chemical language 

 it is called sodium chloride. The symbol is 

 NaCl, which means that a molecule of salt is 

 composed of one atom of sodium and one of 

 chlorine. Chlorine is an exceedingly poison- 

 ous gas. 



Formerly the chemist when he wished to 

 obtain sodium extracted it from common salt 

 and discharged the chlorine gas into the air. 

 It was found that in establishments where the 

 manufacture of sodium was conducted on a 

 large scale the destructive properties of the 

 chlorine discharged into the air was such that 

 all vegetation was killed for some distance 

 around the manufactory. This came to be 

 such a nuisance that the manufacturers were 

 either compelled to stop business or in some 

 way take care of the chlorine. This is done 



