258 Domestic Science 



touching it with the fingers, unless these are quite dry. 

 Start the burning of the sodium by heating the spoon 

 in a Bunsen flame. (Ignore the flame first produced, 

 since this is only the paraffin not removed by the filter- 

 paper burning away.) Lower the spoon into a jar of 

 oxygen and allow it to remain till all burning has ceased. 

 Observe the energetic nature of the combination of the 

 metal with the gas. When the whole apparatus is 

 quite cold, shake up some water in the jar, and dip the 

 end of the spoon into the water. A vigorous action 

 will probably be noticed when this is done, accompanied 

 by a hissing noise. No danger attends this, if the piece 

 of sodium used be not larger than suggested. Test the 

 action of the solution produced upon red and blue 

 litmus papers. The latter will be unaffected, while the 

 red paper, the colour of which has been produced by 

 allowing a small quantity of acid to act upon the 

 colouring-matter, is rendered of a bright blue tint. 

 This result shows that Lavoisier was somewhat hasty 

 in his conclusion that oxygen was typically an " acid- 

 producer". The main product of the combustion of 

 sodium is an oxide called sodium peroxide. When this 

 acts upon water, part of the oxygen is set free, and the 

 remainder of the substance behaves as if it were an 

 oxide with a lesser proportion of oxygen, called sodium 

 oxide. 



Sodium + oxygen = sodium peroxide. 



176. The reactions of the various oxides upon water 

 may be thus represented : 



Carbon dioxide + hydrogen ox id e = hydrogen carbonate 



(water) (carbonic acid) 



Sulphur dioxide + = hydrogen sulphite 



(sulphurous acid) 



J Sulphur trioxidc + ,, ,, hydrogen sulphate ^ 



{ (sulphuric acid) J 



