278 HISTORICAL INTRODUCTION TO CHEMISTRY CHAP. 



there was a vivid action ; alkali and grey metallic particles 

 which dissolve with effervescence in muriatic acid, appeared. 

 The oxides of lead and the oxides of tin were revived still 

 more rapidly ; and when the basis of potash was in excess, 

 an alloy was formed with the revived metal " (A.C.R. 

 VI. 22). 



The decomposition of caustic soda. Davy immediately 

 examined caustic soda to see if he could decompose it as he 

 had done potash. He found that : 



" Soda, when acted upon in the same manner as potash 

 exhibited an analogous result ; but the decomposition 

 demanded greater intensity of action in the batteries, or 

 the alkali was required to be in much thinner and smaller 

 pieces" (A.C.R. VI. 9). 



The " basis of soda " was a white, metallic substance very 

 similar to potassium. 



To the metal thus prepared from soda Davy gave the 

 name SODIUM. 



Physical properties of sodium. The properties of sodium 

 were described as follows : 



" The basis of soda .... is a solid at common tempera- 

 tures. It is white, opaque, and when examined under a 

 film of naphtha, has the lustre and general appearance of 

 silver. It is exceedingly malleable, and is much softer than 

 any of the common metallic substances." 



" It conducts electricity and heat in a similar manner to 

 the basis of potash ; and small globules of it inflame by the 

 voltaic electrical spark, and burn with bright explosions." 



" Its specific gravity is less than that of water. It swims 

 in oil of sassafras of 1-096, water being i, and sinks 

 in naphtha of specific gravity 0-86 1. This circumstance 

 enabled me to ascertain the point with precision. I mixed 

 together oil of sassafras and naphtha, which combine very 

 perfectly, observing the proportions till I had composed a 

 fluid, in which it remained at rest above or below ; and this 

 fluid consisted of nearly twelve parts naphtha, and five of oil 

 of sassafras, which gives a specific gravity to that of water, 



