640 PRINCIPLES OF -CHEMISTRY 



both in chlorine and in oxygen, evolving much heat These properties 

 fere closely connected with its power of taking up oxygen, chlorine, 

 and similar elements from most of their compounds. Just as it removes 

 the oxygen from the oxides of nitrogen and from carbonic anhydride, so 

 also does it .decompose the majority of oxides at definite temperatures. 

 Here the action is essentially the same as in the decomposition of 

 water. Thus, for instance, when acting on magnesium chloride the 

 sodium displaces the magnesium, and when acting on aluminium chloride 

 it displaces metallic aluminium. Sulphur, phosphorus, arsenic and a 

 whole series of other elements, also combine with sodium. 46 



With oxygen sodium unites in three degrees of combination, forming 

 & suboxide Na 4 O, 46 bl an oxide, Na 2 0, and a peroxide, NaO. They are 

 thus termed becaus.e Na 2 O is a stable basio oxide (with water it forms 

 a basic hydroxide), whilst Na 4 and NaO do not form corresponding 

 saline hydrates and salts. The suboxide is a grey inflammable substance 

 which easily decomposes water, disengaging hydrogen ; it is formed 

 by the slow oxidation of sodium at the ordinary temperature. The 

 peroxide is a greenish yellow substance, fusing at a bright red heat ; it 

 is produced by burning sodium in an excess of oxygen, and it yields 

 oxygen when treated with water 



Suboxide : Na 4 O 4- 3H 2 O = 4NaHO + H a 47 

 Oxide: Na 2 4- H 2 O = 2NaHO 48 



Peroxide : Na 2 O a -f H 2 = 2NaHO 



of the substances contained jn the mixture composing naphtha. In order that sodium 

 may retain its lustre in naphtha, secondary octyl alcohol is added. (This alcohol is 

 obtained by distilling castor oil with caustic potash.) Sodium keeps well in a mixture 

 of pure benzene and paraffin. 



46 If sodium does not directly displace the hydrogen in hydrocarbons, still by indirect 

 means compounds may be obtained which contain sodium and hydrocarbon groups.., 

 Some of these compounds have been produced, although not in a pure state. Thus, for i 

 instance, zinc ethyl, Zn (C 3 H 5 ) 2 , when treated with sodium, loses zinc and forms sodium 

 ethyl, C 2 H 5 Na,but this decomposition is not Complete, and the compound formed cannot i 

 be separated by distillation from the remaining zinc ethyl. In this compound the 

 energy of the sodium is clearly manifest, for it reacts with substances containing haloids, 

 oxygen, &c., and directly absorbs carbonic, anhydride, forming a salt of a carboxylic acid 

 ((propionic). 



bu It is even doubtful whether the suboxide exists (see Note 47). 



<7 A compound, NajCl, which 'corresponds with the suboxide, is apparently formed 

 when a galvanic current is parsed, through fused common. salt; the sodium liberated 

 dissolves in the common salt,. and does not separate from the compound either on 

 cooling or on treatment with mercury. It is therefore supposed to be Na^Cl; the 

 more so as the mass obtained gives- hydrogen when treated with water: Na 2 Cl + H.jQ 

 = H + NaHO + NaCl, that is, it acts like suboxide of sodium. If Na^Cl reaHy exists as a 

 Bait, then the corresponding base Na 4 O, according to the rule with other bases of the 

 composition M 4 O, ought to be called a quaternary oxide. According to certain evidence* 

 fysuboxide is formed when .thin sheets or fine drops of sodium slowly oxidise in moist air* 



48 According to observations easily made, sodium when fused in air oxidises but .does 

 hot burn, the combustion only commenoii^ with the formation o! vapour that is> whea 



