CH. IX 



SULPHUR AND PHOSPHORUS 



163 



of sulphur in the mineral is also shown by the pungent 

 odour of burning sulphur which is produced when pyrites 

 is burnt in a current of air ; at the same time the brilliant 

 metallic nodules of the mineral are converted into a red 

 rust-like ash or calx. 



Sulphur present in oil of vitriol. The presence of 

 sulphur in oil of vitriol was also recognised at an early 

 date. Basil Valentine described a method of preparing the 



FIG. 36 RHOMBIC CRYSTALS OF SULPHUR. British Museum (Natural History). 



acid from sulphur with the aid of saltpetre. Conversely, 

 Glauber was able to prepare " flowers of sulphur " from the 

 acid by heating its salts with coal, extracting with water, and 

 acidifying the solution. On account of this relationship the 

 French chemists in 1787 gave to oil of vitriol the name 

 SULPHURIC ACID, whilst its salts were described as 



SULPHATES. 



Stahl (1702) prepares a volatile acid from burning 

 sulphur. The product formed by burning sulphur in air 

 is a pungent gas, which dissolves readily in water to a feebly 



M 2 



