g2 A YEAR IN SCIENCE 



pale yellowish gas, which if collected on a cool surface 

 will be found to be the yellow sulphur with which we 

 started. On cooling, the same changes take place in 

 reverse order. 



This entire cycle of changes through which sulphur 

 has passed is purely physical and due to the different 

 degrees of temperature to which it was subjected. 



Chemical properties. Sulphur burns in the air or in 

 oxygen with a pale blue flame, forming an oxide of 

 sulphur (sulphur dioxide). It unites very readily with 

 most metals, when heated, to form a compound. This 

 is shown by heating a little sulphur on a piece of 

 silver. The black deposit formed is a compound from 

 the union of the sulphur and silver and is called sul- 

 phide of silver. 



Uses. The uses of sulphur are many. We have 

 already mentioned its use in the manufacture of 

 matches. Sulphur is one of the ingredients found in 

 the head of the match. Its kindling point is above that 

 of phosphorus, which produces the spark when lighted, 

 and below that of wood. So the sulphur ignites from 

 the phosphorus and its burning ignites the wood. 



Sulphur dioxide, the gas produced when sulphur 

 burns, has a very suffocating odor. It is impossible 

 for germ life to exist long in its presence ; therefore it 

 is a valuable disinfecting agent. It is very commonly 

 used in fumigating rooms that have been occupied by 

 persons having contagious diseases. This is done by 

 making the room as nearly air tight as possible, then 



