218 



SCIENTIFIC AMUSEMENTS. 



with a perforation in the centre through which a deflagrating 

 spoon can be admitted. Some potassium chlorate is placed in the 



spoon and heated in a 

 flame until the salt is 

 melted and begins to 

 decompose rapidly 

 evolving oxygen (Expt. 

 176) ; the spoon is then 

 quickly introduced 

 into the cylinder of 

 gas through the open- 

 ing in the lid, when 

 the fused chlorate 

 burns freely, any sur- 

 plus gas escaping and 

 also burning at the 

 orifice. 



Here . the action 

 (with hydrogen) is one 

 of simple displacement. 

 Potassium chlorate is 

 a compound of potas- 

 sium chloride and oxy- 

 gen (Expt. 178), and 

 Fig. 94. Oxygen from Potassium chlorate G , x , r , '' 



burning in Coal Gas. when hydrogen acts 



thereon the oxygen 



separates from the potassium chloride and unites with the hydrogen, 

 so that potassium chloride and steam are the products. With 

 coal gas the action is similar but of a somewhat more complex 

 character owing to the more complicated composition of coal gas. 



Expt. 258. To deflagrate Charcoal with Nitre. Fuse some 

 saltpetre in a crucible and then throw in a piece of charcoal 

 previously heated in the lamp flame so as to make it glow and 

 commence to burn ; a brilliant combustion or deflagration will be 

 produced, the chemical action taking place being a somewhat com- 

 plex one ; the saltpetre contains potassium, nitrogen, and oxygen, 

 and in contact with the carbon of the charcoal forms a mixture of 

 carbon dioxide and nitrogen gases which escape, whilst potassium 

 carbonate (a compound of potassium, carbon, and oxygen) remains. 

 On the whole, therefore, the charcoal is partly burnt by oxygen 

 derived from the nitre, which accounts for the large amount of 

 light and heat developed. Sulphur, zinc filings, and many other 

 combustible solids will similarly " deflagrate " when thrown on to 

 melted saltpetre. 



