SODIT.M 527 



but also charcoal, has this property, although hydrogen does not reduce 

 sodium. 37 But still the methods of extracting sodium were very 

 troublesome, and consequently sodium was a great rarity. The principal 

 obstacle to its production was that they endeavoured to condense the 

 easily-oxidising vapours of sodium in vacuum in complicated apparatus. 

 For this reason, when Donny and Maresca, having thoroughly studied 

 the matter, constructed a specially simple condenser, the production of 

 sodium was much facilitated. Furthermore, in practice the most im- 

 portant epoch in the history of the production of sodium is comprised in 

 the investigation of Sainte-Claire Deville, who avoided the complex 

 methods in vogue up to that time, and furnished those simple means by 

 which the production of sodium is now rendered feasible in chemical 

 works. 



For the production of sodium according to the method of Deville, a 

 mixture of sodium carbonate (7 parts) free from water, charcoal (two 

 parts), and lime or chalk (7 parts) is heated. This latter ingredient is 

 only added in order that the sodium carbonate, on fusing, shall not 

 separate from the charcoal. 38 The chalk on being heated loses carbonic 

 -anhydride, leaving infusible lime, which is permeated by the sodium 

 carbonate and forms a thick mass, in which the charcoal is situated, in 

 immediate contact with the sodium carbonate. That is to say, the lime 

 only serves as a mechanical admixture. When the charcoal is heated 



hydroxide was introduced into the upper part. The decomposition was then effected 

 that is, sodium vapours were produced (this experiment was done really with potassium 

 hydroxide). On unfastening the bottle it was found that the iron in the upper part 

 was not oxidised, but only that in the lower part. This may be explained by the decom- 

 position of the alkali into sodium, hydrogen, and oxygen taking place in the upper part, 

 whilst the iron in the lower part absorbed the oxygen set free. If the whole bottle be 

 subjected to the same moderate heat as the lower- extremity, no metallic vapours are 

 formed. Then, according to the hypothesis, the temperature would be insufficient for 

 the dissociation of the sodium hydroxide. 



57 It has been previously remarked (Chapter II. Note 9) that Beketoff showed 

 the displacement of sodium by hydrogen, not from sodium hydroxide but from the oxide 

 Na 2 O ; then, however, only one half is displaced, with the formation of NaHO. 



58 In latter times in England, where the preparation of sodium is at present carried 

 on on a large commercial scale (from 1860 to 1870 it was only manufactured in a few 

 works in France), they have begun to add to Deville's mixture more iron, or iron oxide, 

 which, with the charcoal, gives metallic and carburetted iron, which still further 

 facilitates the decomposition. At present a kilogram of sodium may be purchased 

 for about the same sum (2/-) as a gram cost thirty years ago. The industrial prepa- 

 ration of sodium in large quantities ought not only to influence the extraction of such 

 metals as aluminium (metal of clay and alum), but also many other branches of industry. 

 The method of preparation by means of the action of the galvanic current, proposed and 

 tried many tunes, still requires further improvement. Deville overcame the practical 

 difficulties connected with his process, which is that in use at present, and is distinguished 

 by its simplicity and cheapness; but so far industry has but scantily availed itself of the 

 possibility of obtaining cheap sodium. 



