SODIUM. 4G1 



its transparency in the air. It is decomposed by water, and 

 cannot be formed by uniting its constituent salts. Another 

 compound contains bisulphate of potash ; KO, S 2 O 6 + KO, 

 V^io- This salt is obtained from the mother liquor which remains 

 in the preparation of the teriodate of potash, after treatment with 

 sulphuric acid. When that liquor is evaporated by heat, this 

 salt is deposited in transparent regular crystals. Like the pre- 

 ceding salt it is decomposed by water, and cannot be formed 

 directly. These two salts and the teriodate of potash, merit a 

 re-examination, in reference to their containing water as a con- 

 stituent. 



SECTION II. 

 SODIUM. 



Syn. NATRIUM. Eg. 291 or 23.31; Na. 



Davy obtained this metal by the voltaic decomposition of soda, 

 immediately after the discovery of potassium. An intimate mix- 

 ture of charcoal and carbonate of soda is obtained by calcining 

 acetate of soda, from which sodium is commonly prepared, ac- 

 cording to the method described for potassium, and with greater 

 facility, owing to the superior volatility of this metal. 



Sodium is a white metal having the aspect of silver. Its 

 density is 0.972, at 59, according to Gay-Lussac and Thenard. 

 This metal is so soft, at the usual temperature, that it may be 

 cut with a knife, and yields to the pressure of the fingers ; it is 

 quite liquid at 194. It oxidates spontaneously in the air, al- 

 though not so quickly as potassium ; and when heated nearly 

 to redness takes fire and burns with a yellow flame. Thrown 

 upon water, it oxidates with great vivacity, but without inflam- 

 ing, evolving hydrogen gas, and forming an alkaline solution of 

 soda. When a few drops only of water are applied to sodium, 

 it easily becomes sufficiently hot to take fire. 



As potassium is in some degree characteristic of the vege- 

 table kingdom, so sodium is the alkaline metal of the animal 

 kingdom, its salts being found in all animal fluids. Both of 

 these elements occur in the mineral world ; of the two, per- 

 haps, potassium is most extensively diffused ; felspar, the most 

 common of minerals, containing 12 per cent, of potash, but 



