Combustible Substances. 205 



Mix three parts of sal ammoniac* three of 

 fresh quick-lime, two of flowers of sulphur; 

 distil them With a gradual heat: when the heat 

 rises to a certain degree, the alkali is in a caustic 

 state, combines with the sulphur, and forms a 

 sulphuret much stronger and more penetrating 

 than that formed by fixed alkali. It is called 

 sulphuret of ammonia, or volatile tincture of 

 sulphur, and is administered by some quacks to 

 expel the gout, but very absurdly. This volatile 

 sulphuret emits fumes, and has a disagreeable 

 smell, like all other solutions of sulphur. 



Sulphur is often found in considerable quan- 

 tities in a pure separate state, especially in the 

 neighbourhood of volcanos, or in countries where 

 they have existed. It is contained also in small 

 quantities in the waters of some mineral springs, 

 as those of Harrowgate, for instance. The 

 waters that have a sulphurous smell do not in- 

 deed all contain actual brimstone, but a volatile 

 vapour, producing the same effect as the vapour 

 from a solution of sulphur. 



Sulphur combines with all the other simple 

 combustibles and metals, forming sulphurets; 

 and with some of them in a superabundant dose, 

 forming super-sulphurets. One of these latter is 

 particularly deserving our attention. 



Pyrites, which is a super-sulpliuret of iron, is 

 a mineral of considerable weight, in appearance 

 and colour resembling brass. It exists in va- 

 rious forms ; but the internal structure will ge- 



