CHAPTER XXXI 

 COMPOUNDS OF SODIUM AND POTASSIUM 



WE have already considered sodium and sodium hydroxide 

 (Chap. XIV). In this chapter we take up the other important 

 compounds of sodium and their uses, and we devote some space 

 also to potassium and its more useful compounds. 



In general, we shall find that these metals and their correspond- 

 ing compounds are very much alike in properties. The chief 

 differences are that t^sodiumcompounds are usually cheapen. 

 and that, on account of the difference in the atomic weights of 

 the two elements (sodium 23, potassium 39), smaller weights of jh& 

 sodium compounds suffice for a given use involving chemicaLJn=- 

 teraction. For these reasons the sodium compounds find, in 

 most cases, more applications. 



.T-pi nn.wnl#nt. 1 and botli are very active 



as metallic elements. Their hydroxides being strongly alkaline, 

 the elements are often called the metals of the alkalies. 



SODIUM Na 



Sodium derives its symbol Na from its German name, natrium. 

 All compounds of sodium, when heated with a Bunsen burner, 

 confer a strong yellow tint upon the flame. 



Sodium, Chloride NaCl. Sea water contains about 2.5 per 

 cent of sodium chloride NaCl. The same compound is found in 

 extensive deposits at Stassfurt in Germany, in Cheshire (Eng- 

 land), at Syracuse (New York), at Salina (Kansas), in Utah, 

 California and many other parts of the United States. 



The pure salt is obtained from these deposits by re-crystal- 



365 



