CHAPTER IX 



SULPHUR AND PHOSPHORUS 



A. SULPHUR, SULPHURIC ACID, AND THE SULPHATES. 



Native sulphur. The inflammable mineral known as 

 sulphur, or brimstone (Fig. 36), has been a familiar substance 

 from very early times. Its occurrence in the neighbourhood 

 of volcanoes, and the pungent smell which is produced when 

 it is burnt, caused it to be regarded during many centuries as 

 a symbol of the powers of evil. In alchemistic times it 

 acquired a n'ew significance as one of three principles, 

 mercury, sulphur, and salt, which took the place of the 

 four elements, earth, air, fire, and water, of the classical 

 writers. As representing the principle of inflammability, 

 sulphur was supposed to be present in all combustible sub- 

 stances, just as mercury was supposed to be present in all 

 metals ; much of the early work of Robert Boyle was de- 

 voted to proving the falseness of this assumption. 



Sulphur from pyrites. Sulphur is present in combination 

 with iron in the mineral pyrites or marcasite (Figs. 6, 7, 8, 

 pp. 89), and can be separated from it in part by 

 the action of heat. This method was used in the 

 middle ages for the artificial preparation of sulphur; 

 thus Mayow states that "Vitriols are produced from the 

 stone . . . called Marchasite, and from it on the application 

 of fire the flowers of common sulphur are elicited in con- 

 siderable abundance" (A.C.R. XVII. 28). The presence 



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